Systems and methods for detecting gesture events in a smart home system

ABSTRACT

Hazard detection systems and methods according to embodiments described herein are operative to enable a user to interface with the hazard detection system by performing a touchless gesture. The touchless gesture can be performed in a vicinity of the hazard detection system without requiring physical access to the hazard detection system. This enables the user to interact with the hazard detection system even if it is out of reach. The hazard detection system can detect gestures and perform an appropriate action responsive to the detected gesture. In one embodiment, the hazard detection system can silence its audible alarm or pre-emptively turn off its audible alarm in response to a detected gesture. Gestures can be detected by processing sensor data to determine whether periodic shapes are detected.

CROSS-REFERENCES TO RELATED APPLICATIONS

This patent application is a continuation of U.S. patent applicationSer. No. 15/249,019, filed Aug. 26, 2016 (now U.S. Pat. No. 9,892,623),which is a continuation of U.S. patent application Ser. No. 14/334,430,filed Jul. 17, 2014 (now U.S. Pat. No. 9,449,492), which claims priorityto each of U.S. Provisional Patent Application Nos. 61/847,960, filedJul. 18, 2013, and 61/889,013, filed Oct. 9, 2013. Each of theabove-referenced patent applications is incorporated by reference in itsentirety for all purposes.

TECHNICAL FIELD

This patent specification relates to systems and methods for detectinggesture events with a hazard detection system. More particularly, thispatent specification relates to systems and methods for detectingpatterns in data that potentially represent gesture events.

BACKGROUND

Hazard detection systems such as smoke detectors, carbon monoxidedetectors, combination smoke and carbon monoxide detectors, as well assystems for detecting other dangerous conditions have been used inresidential, commercial, and industrial settings for safetyconsiderations. When these systems detect the presence of a dangerouscondition, they often sound an audible alarm. The alarm is oftencharacterized as having an extremely loud or ear piercing sound, and canbe unpleasant or very uncomfortable to a human listener. Some hazarddetectors may permit a user to press a button located on the cover ofthe unit, sometimes termed a hush button or temporary silence button,when they know an alarm to be caused by a non-emergency situation, suchas smoke from cooking. When the hush button or temporary silence buttonis pressed, the audible alarm noise is temporarily silenced for apredetermined interval of time, such as in the range of four to tenminutes, during which the user has an opportunity to address thesituation, such as by opening a window, without being required to endurethe ear-piercing sound of the alarm. If the condition persists at theend of the predetermined interval of time, then the audible alarm noiseresumes. One issue that can arise in many practical situations is thatthe hazard detector unit is mounted high on a wall or on a ceiling thatis out of the reach of the user, leading many users to seek out aladder, chair, or broomstick in order to press the hush button ortemporary silence button, which can lead to inconvenient, impractical,and/or unsafe scenarios. Other issues arise as would be apparent to aperson skilled in the art in view of the instant disclosure.

SUMMARY

Hazard detection systems and methods according to embodiments describedherein are operative to enable a user to interface with the hazarddetection system by performing a touchless gesture. The touchlessgesture can be performed in a vicinity of the hazard detection systemwithout requiring the user to physically touch the hazard detectionsystem. This enables the user to interact with the hazard detectionsystem even if it is out of reach. The hazard detection system candetect gestures and perform an appropriate action responsive to thedetected gesture. In one embodiment, the hazard detection system cansilence its audible alarm in response to a detected gesture. In anotherembodiment, the hazard detection system can pre-emptively turn off itsaudible alarm in response to a detected gesture. For example, a user maywish to pre-emptively prevent an audible alarm from sounding if she isperforming an activity (e.g., cooking) that may result in an alarmevent, but an alarm event that is not necessarily warranted.

Gestures can be detected using gesture detection circuitry and methodsaccording to various embodiments. The gesture detection circuitry canuse one more sensors to detect one or more objects that may beperforming a gesture. In one embodiment, gestures can be detected usinga motion detector such as a passive infrared sensor. In anotherembodiment, gestures can be detected using a motion detector incombination with one or more ultrasonic sensors.

In one embodiment, a method for processing a gesture to alter a state ofa hazard detection system may be provided. The method can includeconfirming presence of a least one object in at least one ultrasonicdetection field, processing passive infrared (PIR) data being receivedwhile the at least one object is confirmed present in the at least oneultrasonic detection field. The processing can determine determiningwhether a periodic pattern exists in a sample set of the PIR data. Themethod can include selectively altering a state of the hazard detectionsystem when at least one periodic pattern is determined to exist.

In another embodiment, a hazard detection system is provided. The systemcan include at least one hazard detection sensor, circuitry operative tosound an audible alarm in response to a hazard event detected by the atleast one hazard detection sensor, a passive infrared (PIR) sensor thatdetects movement of at least one object, and control circuitry. Thecontrol circuitry may be operative to receive data acquired by the PIRsensor, and use a shape matching algorithm to determine if a gestureevent exists in the received data.

In one embodiment, a method for detecting a user gesture is provided.The method can be implemented by a hazard detection system and caninclude receiving passive infrared red (PIR) signals from a PIR sensor,and selecting a window, wherein the window defines a sample set ofreceived PIR signals used to detect gesture events. The method caninclude calculating a non-wave score for the sample set, calculating awave score for the sample set, scaling the non-wave score by a constant,and determining whether a difference between the scaled non-wave scoreand the wave score exceeds a threshold, wherein when the differenceexceeds the threshold, a gesture pattern is detected in the sample set.

A further understanding of the nature and advantages of the embodimentsdiscussed herein may be realized by reference to the remaining portionsof the specification and the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram of an enclosure with a hazard detection system,according to some embodiments;

FIG. 2 shows an illustrative block diagram of a hazard detection systembeing used in an illustrative enclosure, according to some embodiments;

FIG. 3 shows an illustrative circuit schematic of a hazard detectionsystem, according to some embodiments;

FIGS. 4A-4E show different views of a hazard detection system along withits illustrative positioning of several interface sensors, according tosome embodiments;

FIG. 5A shows illustrative detection fields emanating from interfacesensors of hazard detection system mounted in a first position,according to some embodiments;

FIG. 5B shows illustrative detection fields emanating from interfacesensors of hazard detection system mounted in a second position,according to some embodiments;

FIGS. 6A-6D show illustrative snapshots in time in which a person uses agesture to silence an audible alarm, according to some embodiment;

FIG. 7 shows an illustrative timing diagram of various components of ahazard detection system, according to some embodiments;

FIG. 8 shows an illustrative detection field for a PIR sensor, accordingto some embodiments;

FIGS. 9A-9D show several different illustrative graphs showing PIRsensor data according to some embodiments;

FIG. 10 shows illustrative waveforms of raw and filtered PIR data,according to some embodiments;

FIG. 11 shows an illustrative process in which a hazard detection systemsilences an audible alarm in response to monitoring a gesture, accordingto some embodiments;

FIG. 12 shows illustrative wave diagrams that may form the calibrationbasis of two different ultrasonic sensors according to an examplescenario;

FIG. 13 shows illustrative wave diagrams according to an examplescenario;

FIGS. 14A-14C show an illustrative process for operating a hazarddetection system with gesture hush capability, according to someembodiments;

FIG. 15 shows an illustrative process in which a hazard detection systemsilences an audible alarm in response to monitoring a gesture, accordingto some embodiments;

FIG. 16 shows an illustrative process for operating a hazard detectionsystem equipped with at least one ultrasonic sensor, according to someembodiments; and

FIG. 17 shows an illustrative process for operating a hazard detectionsystem equipped with a PIR sensor and at least one ultrasonic sensor,according to some embodiments;

FIG. 18 shows an exemplary calibration matrix, according to someembodiments;

FIG. 19A shows an illustrative waveform that can represent distancesdetected by one of the ultrasonic sensors over time, according to someembodiments;

FIG. 19B shows a derivative waveform of the waveform of FIG. 19A,according to some embodiments;

FIG. 20 shows an illustrative gesture waveform, which may represent awave gesture, according to some embodiments;

FIG. 21 shows illustrative buffer containing gesture waveforms,according to some embodiments;

FIG. 22 illustrates a timing diagram of a PIR waveform according to anembodiment;

FIG. 23 shows an illustrative waveform of PIR waveform according to anembodiment;

FIG. 24 shows an illustrative PIR waveform sampling within a window, andseveral different waving periods according to an embodiment; and

FIG. 25 shows an illustrative flowchart of steps that may be executed bya shape matching algorithm according to an embodiment.

DETAILED DESCRIPTION OF THE DISCLOSURE

In the following detailed description, for purposes of explanation,numerous specific details are set forth to provide a thoroughunderstanding of the various embodiments. Those of ordinary skill in theart will realize that these various embodiments are illustrative onlyand are not intended to be limiting in any way. Other embodiments willreadily suggest themselves to such skilled persons having the benefit ofthis disclosure.

In addition, for clarity purposes, not all of the routine features ofthe embodiments described herein are shown or described. One of ordinaryskill in the art would readily appreciate that in the development of anysuch actual embodiment, numerous embodiment-specific decisions may berequired to achieve specific design objectives. These design objectiveswill vary from one embodiment to another and from one developer toanother. Moreover, it will be appreciated that such a development effortmight be complex and time-consuming but would nevertheless be a routineengineering undertaking for those of ordinary skill in the art havingthe benefit of this disclosure.

It is to be appreciated that while one or more hazard detectionembodiments are described further herein in the context of being used ina residential home, such as a single-family residential home, the scopeof the present teachings is not so limited. More generally, hazarddetection systems are applicable to a wide variety of enclosures suchas, for example, duplexes, townhomes, multi-unit apartment buildings,hotels, retail stores, office buildings, and industrial buildings.Further, it is understood that while the terms user, customer,installer, homeowner, occupant, guest, tenant, landlord, repair person,and the like may be used to refer to the person or persons who areinteracting with the hazard detector in the context of one or morescenarios described herein, these references are by no means to beconsidered as limiting the scope of the present teachings with respectto the person or persons who are performing such actions.

FIG. 1 is a diagram illustrating an exemplary enclosure 100 using hazarddetection system 105, remote hazard detection system 107, thermostat110, remote thermostat 112, heating, cooling, and ventilation (HVAC)system 120, router 122, computer 124, and central panel 130 inaccordance with some embodiments. Enclosure 100 can be, for example, asingle-family dwelling, a duplex, an apartment within an apartmentbuilding, a warehouse, or a commercial structure such as an office orretail store. Hazard detection system 105 can be battery powered, linepowered, or be line powered with a battery backup. Hazard detectionsystem 105 can include one or more processors, multiple sensors,non-volatile storage, and other circuitry to provide desired safetymonitoring and user interface features. Some user interface features mayonly be available in line powered embodiments due to physicallimitations and power constraints. In addition, some features common toboth line and battery powered embodiments may be implementeddifferently. Hazard detection system 105 can include the following powerconsuming components: low power wireless personal area network (LoWPAN)circuitry, a system processor, a safety processor, non-volatile memory(e.g., Flash), WiFi circuitry, an ambient light sensor (ALS), a smokesensor, a carbon monoxide (CO) sensor, one or more temperature sensors,one or more ultrasonic sensors, a passive infra-red (PIR) sensor, aspeaker, one or more LED's, and a buzzer. It is understood multipleinstances of the same component may exist, whereas other components mayonly exist in one instance.

Hazard detection system 105 can monitor environmental conditionsassociated with enclosure 100 and alarm occupants when an environmentalcondition exceeds a predetermined threshold. The monitored conditionscan include, for example, smoke, heat, humidity, carbon monoxide, carbondioxide, radon, and other gasses. In addition to monitoring the safetyof the environment, hazard detection system 105 can provide several userinterface features not found in conventional alarm systems. These userinterface features can include, for example, vocal alarms, voice setupinstructions, cloud communications (e.g. push monitored data to thecloud, or push notifications to a mobile phone, receive commands fromthe cloud such as a hush command), device-to-device communications(e.g., communicate with other hazard detection systems in theenclosure), visual safety indicators (e.g., display of a green lightindicates it is safe and display of a red light indicates danger),tactile and non-tactile input command processing, and software updates.

It should be understood that hazard detection system 105 may beimplemented as a smart home device. Thus, although the discussion of thehazard detection system is described primarily with reference tospecific hazards (e.g., smoke, CO, heat), the hazard detection systemmay provide additional features and functionality unrelated to thosehazards. For example, the hazard detection system may monitor manydifferent conditions. These conditions can include motions, sounds, andsmells. These conditions can also include data supplied by remotesensors (e.g., armbands, door sensors, window sensors, personal mediadevices).

Hazard detection system 105 can implement multi-criteria state machinesaccording to various embodiments described herein to provide advancedhazard detection and advanced user interface features such aspre-alarms. In addition, the multi-criteria state machines can managealarming states and pre-alarming states and can include one or moresensor state machines that can control the alarming states and one ormore system state machines that control the pre-alarming states. Eachstate machine can transition among any one of its states based on sensordata values, hush events, and transition conditions. The transitionconditions can define how a state machine transitions from one state toanother, and ultimately, how hazard detection system 105 operates.Hazard detection system 105 can use a dual processor arrangement toexecute the multi-criteria state machines according to variousembodiments. The dual processor arrangement enables hazard detectionsystem 105 to manage the alarming and pre-alarming states in a mannerthat uses minimal power while simultaneously providing relativelyfailsafe hazard detection and alarming functionality. Additional detailsof multi-criteria state machines can be found, for example, in commonlyassigned U.S. Pat. No. 9,412,258, the disclosure of which isincorporated by reference herein its entirety.

Enclosure 100 can include any number of hazard detection systems. Forexample, as shown, hazard detection system 107 is another hazarddetection system, which may be similar to system 105. In one embodiment,both systems 105 and 107 can be battery powered systems. In anotherembodiment, system 105 may be line powered, and system 107 may bebattery powered. Moreover, a hazard detection system can be installedoutside of enclosure 100.

Thermostat 110 can be one of several thermostats that controls HVACsystem 120. Thermostat 110 can be referred to as the “primary”thermostat because it is electrically connected to actuate all or partof an HVAC system, by virtue of an electrical connection to HVAC controlwires (e.g. W, G, Y, etc.) leading to HVAC system 120. Thermostat 110can include one or more sensors to gather data from the environmentassociated with enclosure 100. For example, a sensor may be used todetect occupancy, temperature, light and other environmental conditionswithin enclosure 100. Remote thermostat 112 can be referred to as an“auxiliary” thermostat because it may not be electrically connected toactuate HVAC system 120, but it too may include one or more sensors togather data from the environment associated with enclosure 100 and cantransmit data to thermostat 110 via a wired or wireless link. Forexample, thermostat 112 can wirelessly communicate with and cooperateswith thermostat 110 for improved control of HVAC system 120. Thermostat112 can provide additional temperature data indicative of its locationwithin enclosure 100, provide additional occupancy information, orprovide another user interface for the user (e.g., to adjust atemperature setpoint).

Hazard detection systems 105 and 107 can communicate with thermostat 110or thermostat 112 via a wired or wireless link. For example, hazarddetection system 105 can wirelessly transmit its monitored data (e.g.,temperature and occupancy detection data) to thermostat 110 so that itis provided with additional data to make better informed decisions incontrolling HVAC system 120. Moreover, in some embodiments, data may betransmitted from one or more of thermostats 110 and 112 to one or moreof hazard detections systems 105 and 107 via a wired or wireless link.

Central panel 130 can be part of a security system or other mastercontrol system of enclosure 100. For example, central panel 130 may be asecurity system that may monitor windows and doors for break-ins, andmonitor data provided by motion sensors. In some embodiments, centralpanel 130 can also communicate with one or more of thermostats 110 and112 and hazard detection systems 105 and 107. Central panel 130 mayperform these communications via wired link, wireless link, or acombination thereof. For example, if smoke is detected by hazarddetection system 105, central panel 130 can be alerted to the presenceof smoke and make the appropriate notification, such as displaying anindicator that a particular zone within enclosure 100 is experiencing ahazard condition.

Enclosure 100 may further include a private network accessible bothwirelessly and through wired connections and may also be referred to asa Local Area Network or LAN. Network devices on the private network caninclude hazard detection systems 105 and 107, thermostats 110 and 112,computer 124, and central panel 130. In one embodiment, the privatenetwork is implemented using router 122, which can provide routing,wireless access point functionality, firewall and multiple wiredconnection ports for connecting to various wired network devices, suchas computer 124. Wireless communications between router 122 andnetworked devices can be performed using an 802.11 protocol. Router 122can further provide network devices access to a public network, such asthe Internet or the Cloud, through a cable-modem, DSL modem and anInternet service provider or provider of other public network service.Public networks like the Internet are sometimes referred to as aWide-Area Network or WAN.

Access to the Internet, for example, may enable networked devices suchas system 105 or thermostat 110 to communicate with a device or serverremote to enclosure 100. The remote server or remote device can host anaccount management program that manages various networked devicescontained within enclosure 100. For example, in the context of hazarddetection systems according to embodiments discussed herein, system 105can periodically upload data to the remote server via router 122. Inaddition, if a hazard event is detected, the remote server or remotedevice can be notified of the event after system 105 communicates thenotice via router 122. Similarly, system 105 can receive data (e.g.,commands or software updates) from the account management program viarouter 122.

Hazard detection system 105 can operate in one of several differentpower consumption modes. Each mode can be characterized by the featuresperformed by system 105 and the configuration of system 105 to consumedifferent amounts of power. Each power consumption mode corresponds to aquantity of power consumed by hazard detection system 105, and thequantity of power consumed can range from a lowest quantity to a highestquantity. One of the power consumption modes corresponds to the lowestquantity of power consumption, and another power consumption modecorresponds to the highest quantity of power consumption, and all otherpower consumption modes fall somewhere between the lowest and thehighest quantities of power consumption. Examples of power consumptionmodes can include an Idle mode, a Log Update mode, a Software Updatemode, an Alarm mode, a Pre-Alarm mode, a Hush mode, and a Night Lightmode. These power consumption modes are merely illustrative and are notmeant to be limiting. Additional or fewer power consumption modes mayexist. Moreover, any definitional characterization of the differentmodes described herein is not meant to be all inclusive, but rather, ismeant to provide a general context of each mode.

FIG. 2 shows an illustrative block diagram of hazard detection system205 being used in an illustrative enclosure 200 in accordance with someembodiments. FIG. 2 also shows optional hazard detection system 207 androuter 222. Hazard detection systems 205 and 207 can be similar tohazard detection systems 105 and 107 in FIG. 1, enclosure 200 can besimilar to enclosure 100 in FIG. 1, and router 222 can be similar torouter 122 in FIG. 1. Hazard detection system 205 can include severalcomponents, including system processor 210, high-power wirelesscommunications circuitry 212 and antenna, low-power wirelesscommunications circuitry 214 and antenna, non-volatile memory 216,speaker 218, sensors 220, which can include one or more safety sensors221 and one or more non-safety sensors 222, safety processor 230, alarm234, power source 240, power conversion circuitry 242, high qualitypower circuitry 243, and power gating circuitry 244. Hazard detectionsystem 205 is operative to provide failsafe safety detection featuresand user interface features using circuit topology and power budgetingmethods that minimize power consumption. The components of system 205and an exemplary circuit topology are discussed in connection with FIGS.2 and 3, and methods and circuitry for detecting gestures are discussedin connection with FIGS. 4-25.

Hazard detection system 205 can use a bifurcated processor circuittopology for handling the features of system 205. Both system processor210 and safety processor 230 can exist on the same circuit board withinsystem 205, but perform different tasks. System processor 210 is alarger more capable processor that can consume more power than safetyprocessor 230. That is, when both processors 210 and 230 are active,processor 210 consumes more power than processor 230. Similarly, whenboth processors are inactive, processor 210 still consumes more powerthan processor 230. System processor 210 can be operative to processuser interface features and monitor interface sensors 220. For example,processor 210 can direct wireless data traffic on both high and lowpower wireless communications circuitry 212 and 214, access non-volatilememory 216, communicate with processor 230, and cause audio to beemitted from speaker 218. As another example, processor 210 can monitorinterface sensors 220 to determine whether any actions need to be taken(e.g., shut off a blaring alarm in response to a user detected action tohush the alarm).

Safety processor 230 can be operative to handle safety related tasks ofsystem 205, or other types of tasks that involve monitoringenvironmental conditions (such as temperature, humidity, smoke, carbonmonoxide, movement, light intensity, etc.) exterior to the hazarddetection system 205. Safety processor 230 can poll one or more ofsensors 220 and activate alarm 234 when one or more of sensors 220indicate a hazard event is detected. Processor 230 can operateindependently of processor 210 and can activate alarm 234 regardless ofwhat state processor 210 is in. For example, if processor 210 isperforming an active function (e.g., performing a WiFi update) or isshut down due to power constraints, processor 230 can activate alarm 234when a hazard event is detected. In some embodiments, the softwarerunning on processor 230 may be permanently fixed and may never beupdated via a software or firmware update after system 205 leaves thefactory.

Compared to processor 210, processor 230 is a less power consumingprocessor. Thus by using processor 230 in lieu of processor 210 tomonitor a subset of sensors 220 yields a power savings. If processor 210were to constantly monitor sensors 220, the power savings may not berealized. In addition to the power savings realized by using processor230 for monitoring the subset of sensors 220, bifurcating the processorsalso ensures that the safety monitoring and core alarming features ofsystem 205 will operate regardless of whether processor 210 isfunctioning. By way of example and not by way of limitation, systemprocessor 210 may comprise a relatively high-powered processor such asFreescale Semiconductor K60 Microcontroller, while safety processor 230may comprise a relatively low-powered processor such as a FreescaleSemiconductor KL15 Microcontroller. Overall operation of hazarddetection system 205 entails a judiciously architected functionaloverlay of system processor 210 and safety processor 230, with systemprocessor 210 performing selected higher-level, advanced functions thatmay not have been conventionally associated with hazard detection units(for example: more advanced user interface and communications functions;various computationally-intensive algorithms to sense patterns in userbehavior or patterns in ambient conditions; algorithms for governing,for example, the brightness of an LED night light as a function ofambient brightness levels; algorithms for governing, for example, thesound level of an onboard speaker for home intercom functionality;algorithms for governing, for example, the issuance of voice commands tousers; algorithms for uploading logged data to a central server;algorithms for establishing network membership; algorithms forfacilitating updates to the programmed functionality of one or moreelements of the hazard detection system 205 such as the safety processor230, the high power wireless communications circuitry 212, the low powerwireless communications circuitry 214, the system processor 210 itself,etc., and so forth), and with safety processor 230 performing the morebasic functions that may have been more conventionally associated withhazard detection units (e.g., smoke and CO monitoring, actuation ofshrieking/buzzer alarms upon alarm detection). By way of example and notby way of limitation, system processor 210 may consume on the order of18 mW when it is in a relatively high-power active state and performingone or more of its assigned advanced functionalities, whereas safetyprocessor 230 may only consume on the order of 0.05 mW when it isperforming its basic monitoring functionalities. However, again by wayof example and not by way of limitation, system processor 210 mayconsume only on the order of 0.005 mW when in a relatively low-powerinactive state, and the advanced functions that it performs arejudiciously selected and timed such the system processor is in therelatively high power active state only about 0.05% of the time, andspends the rest of the time in the relatively low-power inactive state.Safety processor 230, while only requiring an average power draw of 0.05mW when it is performing its basic monitoring functionalities, should ofcourse be performing its basic monitoring functionalities 100% of thetime. According to one or more embodiments, the judiciously architectedfunctional overlay of system processor 210 and safety processor 230 isdesigned such that hazard detection system 205 can perform basicmonitoring and shriek/buzzer alarming for hazard conditions even in theevent that system processor 210 is inactivated or incapacitated, byvirtue of the ongoing operation of safety processor 230. Therefore,while system processor 210 is configured and programmed to provide manydifferent capabilities for making hazard detection unit 205 anappealing, desirable, updatable, easy-to-use, intelligent,network-connected sensing and communications node for enhancing thesmart-home environment, its functionalities are advantageously providedin the sense of an overlay or adjunct to the core safety operationsgoverned by safety processor 230, such that even in the event there areoperational issues or problems with system processor 210 and itsadvanced functionalities, the underlying safety-related purpose andfunctionality of hazard detector 205 by virtue of the operation ofsafety processor 230 will continue on, with or without system processor210 and its advanced functionalities.

High power wireless communications circuitry 212 can be, for example, aWi-Fi module capable of communicating according to any of the 802.11protocols. For example, circuitry 212 may be implemented using Broadcompart number BCM43362, available in a module from Murata. Depending on anoperating mode of system 205, circuitry 212 can operate in a low power“sleep” state or a high power “active” state. For example, when system205 is in an Idle mode, circuitry 212 can be in the “sleep” state. Whensystem 205 is in a non-Idle mode such as Wi-Fi update mode, softwareupdate mode, or alarm mode, circuitry 212 can be in an active state. Forexample, when system 205 is in an active alarm mode, high powercircuitry 212 may communicate with router 222 so that a message can besent to a remote server or device.

Low power wireless communications circuitry 214 can be a low powerWireless Personal Area Network (6LoWPAN) module or a ZigBee modulecapable of communicating according to a 802.15.4 protocol. For example,in one embodiment, circuitry 214 can be part number EM357 SoC availablefrom Silicon Laboratories. Depending on the operating mode of system205, circuitry 214 can operate in a relatively low power “listen” stateor a relatively high power “transmit” state. When system 205 is in theIdle, WiFi update, or software update modes, circuitry 214 can be in the“listen” state. When system 205 is in the Alarm mode, circuitry 214 cantransmit data so that the low power wireless communications circuitry insystem 207 can receive data indicating that system 205 is alarming.Thus, even though it is possible for high power wireless communicationscircuitry 212 to be used for listening for alarm events, it is morepower efficient to use low power circuitry 214 for this purpose. Powersavings is further realized when several hazard detection systems orother systems having low power circuitry 214 form an interconnectedwireless network.

Power savings is also realized because in order for low power circuitry214 to continually listen for data transmitted from other low powercircuitry, circuitry 214 must constantly be operating in its “listening”state. This state consumes power, and although it may consume more powerthan high power circuitry 212 operating in its sleep state, the powersaved versus having to periodically activate high power circuitry 214 issubstantial. When high power circuitry 212 is in its active state andlow power circuitry 214 is in its transmit state, high power circuitry212 consumes substantially more power than low power circuitry 214.

In some embodiments, low power wireless communications circuitry 214 canbe characterized by its relatively low power consumption and its abilityto wirelessly communicate according to a first protocol characterized byrelatively low data rates, and high power wireless communicationscircuitry 212 can be characterized by its relatively high powerconsumption and its ability to wirelessly communicate according to asecond protocol characterized by relatively high data rates. The secondprotocol can have a much more complicated modulation than the firstprotocol.

In some embodiments, low power wireless communications circuitry 214 maybe a mesh network compatible module that does not require an accesspoint or a router in order to communicate to devices in a network. Meshnetwork compatibility includes provisions that enable mesh networkcompatible modules to keep track of other nearby mesh network compatiblemodules so that data can be passed through neighboring modules. Meshnetwork compatibility is essentially the hallmark of the 802.15.4protocol. In contrast, high power wireless communications circuitry 212is not a mesh network compatible module and requires an access point orrouter in order to communicate to devices in a network. Thus, if a firstdevice having circuitry 212 wants to communicate data to another devicehaving circuitry 212, the first device has to communicate with therouter, which then transmits the data to the second device. Thus, thereis no device-to-device communication per se when circuitry 212 requiresuse of a router. In other embodiments, circuitry 212 can performdevice-to-device communication using a Wi-Fi Direct communicationsprotocol. The Wi-Fi Direct communications standard can enable devices toconnect easily with each other without requiring a router. For example,an exemplary use of Wi-Fi Direct can enable hazard detection system 105to directly communicate with thermostat 110.

Non-volatile memory 216 can be any suitable permanent memory storagesuch as, for example, NAND Flash, a hard disk drive, NOR, ROM, or phasechange memory. In one embodiment, non-volatile memory 216 can storeaudio clips that can be played back by speaker 218. The audio clips caninclude installation instructions or warning in one or more languages.Speaker 218 can be any suitable speaker operable to playback sounds oraudio files. Speaker 218 can include an amplifier (not shown).

Interface sensors 220 can includes sensors that are monitored by systemprocessor 210 and safety sensors 232 can include sensors that aremonitored by safety processor 230. Sensors 220 and 232 can be mounted toa printed circuit board (e.g., the same board processor 210 and 230 aremounted to), a flexible printed circuit board, a housing of system 205,or a combination thereof. Interface sensors 220 can be non-safetyrelated sensors. Interface sensor 220 can include one or more ultrasonicsensors 221, which generate high frequency sound waves and determinewhich wave(s) are received back by the sensor. Interface sensors 220 caninclude a passive infra-red (PIR) sensor 222. PIR sensor 222 can be usedfor various motion detection features. A PIR sensor can measure infraredlight radiating from objects in its field of view. In one embodiment,one of the user interface features is a gesture hush feature, a featurein which a user performs a gesture (e.g., a wave motion) in the vicinityof system 205 to cause it to turn off or silence alarm 234 if it isblaring. One or more of ultrasonic sensors 221, PIR sensor 220, or acombination of both ultrasonic sensors 221 can be used to detect thisgesture in accordance with various embodiments. The gesture hush featureand systems and methods for detecting and processing the gesture hushfeature are discussed in more detail below in connection with FIGS.4-13. Interface sensors 220 may optionally include an ambient light(ALS) sensor and a push-button sensor. An ALS sensor detects ambientlight and the push-button sensor can be a switch, for example, thatdetects a user's press of the switch.

Safety sensors 232 can include a smoke detector, a carbon monoxide (CO)sensor, temperature and humidity sensor, one or more thermistors. Smokedetectors detect smoke and typically use optical detection, ionization,or air sampling techniques. A CO sensor can detect the presence ofcarbon monoxide gas, which in the home, is typically generated by openflames, space heaters, water heaters, blocked chimneys, and automobiles.The material used in electrochemical CO sensors typically has a 5-7 yearlifespan. Thus, after 5-7 year period has expired, the CO sensor shouldbe replaced. A temperature and humidity sensor can provide relativelyaccurate readings of temperature and relatively humidity. A thermistoris a type of resistor whose resistance varies based on temperature.Thermistors can include NTC type thermistors or PTC type thermistors.Safety sensors 232 can optionally include PIR sensor, an ambient lightsensor, and a push-button sensor. If interface sensors 220 do notinclude the PIR sensor, ambient light sensor, or push-button sensor,then safety sensors 232 can include them.

Sensors 220 can be monitored by system processor 210 and safetyprocessor 230, and can include safety sensors 221 and non-safety sensors222. One or more of sensors 220 may be exclusively monitored by one ofsystem processor 210 and safety processor 230. As defined herein,monitoring a sensor refers to a processor's ability to acquire data fromthat monitored sensor. That is, one particular processor may beresponsible for acquiring sensor data, and possibly storing it in asensor log, but once the data is acquired, it can be made available toanother processor either in the form of logged data or real-time data.For example, in one embodiment, system processor 210 may monitor one ofnon-safety sensors 222, but safety processor 230 cannot monitor thatsame non-safety sensor. In another embodiment, safety processor 230 maymonitor each of the safety sensors 221, but provide the acquired sensordata to system processor 210.

Safety sensors 221 can include sensors necessary for ensuring thathazard detection system 205 can monitor its environment for hazardousconditions and alert users when hazardous conditions are detected, andall other sensors not necessary for detecting a hazardous condition arenon-safety sensors 222. In some embodiments, safety sensors 221 includeonly those sensors necessary for detecting a hazardous condition. Forexample, if the hazardous condition includes smoke and fire, then thesafety sensors would only include a smoke sensor and at least one heatsensor. Other sensors, such as non-safety sensors, could be included aspart of system 205, but would not be needed to detect smoke or fire. Asanother example, if the hazardous condition includes carbon monoxide,then the safety sensor would be a carbon monoxide sensor, and no othersensor would be needed to perform this task.

Thus, sensors deemed necessary can vary based on the functionality andfeatures of hazard detection system 205. In one embodiment, hazarddetection system 205 can be a combination smoke, fire, and carbonmonoxide alarm system. In such an embodiment, detection system 205 caninclude the following necessary safety sensors 221: a smoke detector, acarbon monoxide (CO) sensor, and one or more heat sensors. Smokedetectors detect smoke and typically use optical detection, ionization,or air sampling techniques. A CO sensor can detect the presence ofcarbon monoxide gas, which, in the home, is typically generated by openflames, space heaters, water heaters, blocked chimneys, and automobiles.The material used in electrochemical CO sensors typically has a 5-7 yearlifespan. Thus, after 5-7 year period has expired, the CO sensor shouldbe replaced. A heat sensor can be a thermistor, which is a type ofresistor whose resistance varies based on temperature. Thermistors caninclude negative temperature coefficient (NTC) type thermistors orpositive temperature coefficient (PTC) type thermistors. Furthermore, inthis embodiment, detection system 205 can include the followingnon-safety sensors 222: a humidity sensor, an ambient light sensor, apush-button sensor, a passive infra-red (PIR) sensor, and one or moreultrasonic sensors. A temperature and humidity sensor can providerelatively accurate readings of temperature and relative humidity. Anambient light sensor (ALS) sensor detects ambient light and thepush-button sensor can be a switch, for example, that detects a user'spress of the switch. PIR sensor 222 can be used for various motiondetection features. A PIR sensor can measure infrared light radiatingfrom objects in its field of view. Ultrasonic sensors can be used todetect the presence of an object. Such sensors can generate highfrequency sound waves and determine which wave(s) are received back bythe sensor. Sensors 220 can be mounted to a printed circuit board (e.g.,the same board that processors 210 and 230 are mounted to), a flexibleprinted circuit board, a housing of system 205, or a combinationthereof.

In some embodiments, data acquired from one or more non-safety sensors222 can be acquired by the same processor used to acquire data from oneor more safety sensors 221. For example, safety processor 230 may beoperative to monitor both safety and non-safety sensors 221 and 222 forpower savings reasons, as discussed above. Although safety processor 230does not need any of the data acquired from non-safety sensor 222 toperform its hazard monitoring and alerting functions, the non-safetysensor data can be utilized to provide enhanced hazard system 205functionality.

Alarm 234 can be any suitable alarm that alerts users in the vicinity ofsystem 205 of the presence of a hazard condition. Alarm 234 can also beactivated during testing scenarios. Alarm 234 can be a piezo-electricbuzzer, for example.

Power source 240 can supply power to enable operation of system 205 andcan include any suitable source of energy. Embodiments discussed hereincan include AC line powered, battery powered, a combination of AC linepowered with a battery backup, and externally supplied DC power (e.g.,USB supplied power). Embodiments that use AC line power, AC line powerwith battery backup, or externally supplied DC power may be subject todifferent power conservation constraints than battery only embodiments.Battery powered embodiments are designed to manage power consumption ofits finite energy supply such that hazard detection system 205 operatesfor a minimum period of time. In some embodiments, the minimum period oftime can be one (1) year, three (3) years or seven (7) years. In otherembodiments, the minimum period of time can be at least seven (7) years,eight (8) years, nine (9) years, or ten (10) years. Line poweredembodiments are not as constrained because their energy supply isvirtually unlimited. Line powered with battery backup embodiments mayemploy power conservation methods to prolong the life of the backupbattery.

In battery only embodiments, power source 240 can include one or morebatteries or a battery pack. The batteries can be constructed fromdifferent compositions (e.g., alkaline or lithium iron disulfide) anddifferent end-user configurations (e.g., permanent, user replaceable, ornon-user replaceable) can be used. In one embodiment, six cells ofLi-FeS₂ can be arranged in two stacks of three. Such an arrangement canyield about 27000 mWh of total available power for system 205.

Power conversion circuitry 242 includes circuitry that converts powerfrom one level to another. Multiple instances of power conversioncircuitry 242 may be used to provide the different power levels neededfor the components within system 205. One or more instances of powerconversion circuitry 242 can be operative to convert a signal suppliedby power source 240 to a different signal. Such instances of powerconversion circuitry 242 can exist in the form of buck converters orboost converters. For example, alarm 234 may require a higher operatingvoltage than high power wireless communications circuitry 212, which mayrequire a higher operating voltage than processor 210, such that allrequired voltages are different the voltage supplied by power source240. Thus, as can be appreciated in this example, at least threedifferent instances of power conversion circuitry 242 are required.

High quality power circuitry 243 is operative to condition a signalsupplied from a particular instance of power conversion circuitry 242(e.g., a buck converter) to another signal. High quality power circuitry243 may exist in the form of a low-dropout regulator. The low-dropoutregulator may be able to provide a higher quality signal than thatprovided by power conversion circuitry 242. Thus, certain components maybe provided with “higher” quality power than other components. Forexample, certain safety sensors such as smoke detectors and CO sensorsmay require a relatively stable voltage in order to operate properly.

Power gating circuitry 244 can be used to selectively couple andde-couple components from a power bus. De-coupling a component from apower bus insures that the component does not incur any quiescentcurrent loss, and therefore can extend battery life beyond that which itwould be if the component were not so de-coupled from the power bus.Power gating circuitry 244 can be a switch such as, for example, aMOSFET transistor. Even though a component is de-coupled from a powerbus and does not incur any current loss, the power gating circuitryitself may consume a finite amount of power. This finite powerconsumption, however, is less than the quiescent power loss of thecomponent.

It is understood that although hazard detection system 205 is describedas having two separate processors, system processor 210 and safetyprocessor 230, which may provide certain advantages as describedhereinabove and hereinbelow, including advantages with regard to powerconsumption as well as with regard to survivability of core safetymonitoring and alarming in the event of advanced feature provisionissues, it is not outside the scope of the present teachings for one ormore of the various embodiments discussed herein to be executed by oneprocessor or by more than two processors.

FIG. 3 shows an illustrative circuit schematic of hazard detectionsystem 300 according to an embodiment. The circuit schematic is a moredetailed illustrative representation of hazard detection system 205 (ofFIG. 2) and shows, among other things, power consuming components, thepower busses supplying power to the components, and gating circuitry forselecting coupling and de-coupling components to a power bus. Hazarddetection system 300 can be powered solely by one or more batteries anduses a power budgeting scheme so that the one or more batteries canpower system 300 for a minimum operational lifetime (e.g., of at leastseven (7) years). The power budgeting scheme further enables system 300to operate according to any one of several different modes (e.g., Idle,WiFi update, Software update, and Alarm) for a mode-specified period oftime (e.g., WiFi update mode is performed once a day) during the minimumoperational lifetime. In the discussion that follows, the circuitarrangement of system 300 illustrates how system 300 is able to manageits power consumption, while providing enhanced user interactionfeatures as well as robust hazard detection.

Hazard detection system 300 includes battery system 301 operative toprovide a DC power source to power bus 308. The DC power source canexist on power bus 308 at a first voltage level. The voltage level maychange slightly depending on various conditions, such as changes intemperature. Depending on composition of DC power source (e.g., alkalineor Lithium-based chemistries), the voltage level can remain at arelatively constant voltage level (e.g., 4.5 volts) or it may remainwithin a pre-defined range of voltage levels during the operational lifeof system 300. The voltage level may drop substantially when the energystored in battery system 301 falls below a predetermined threshold(e.g., when the batteries are effectively dead). Battery system 301 caninclude battery cell group 302 and battery cell group 305. Each ofbattery cell groups 302 and 305 can include one or more battery cells.In one embodiment, each cell group includes three battery cells. Asshown, battery cell group 302 is coupled to diode 304 and to safetyprocessor 330 via bus 303 and gating circuitry 351. Safety processor 330is similar in many respects to safety processor 230 (discussed above inconnection with FIG. 2). Battery cell group 305 is coupled to diode 307and to safety processor 330 via bus 306 and gating circuitry 352. Safetyprocessor 330 can temporarily close gating circuitry 351 and 352 tomeasure the voltages of battery groups 302 and 305, respectively. Afterthe measurement is complete, safety processor 330 can open gatingcircuitry 351 and 352. Diodes 304 and 307 are coupled to power bus 308.

Power bus 308 is coupled to power converter circuitry 340, powerconverter circuitry 342, power converter circuitry 344, power convertercircuitry 346, ultrasonic sensor 320, smoke detector 324, and displaymodule 328 (e.g., light emitting diode (LED)) via power gating circuitry353. As discussed above in connection with FIG. 2, power convertingcircuitry is operative to convert a signal from one level to another.Ultrasonic sensor 320 can be similar to the ultrasonic sensor referencedin connection with interface sensors 220 (of FIG. 2). Although only oneultrasonic sensor is shown, system 300 can include more than oneultrasonic sensor. In one embodiment, system 300 can include twoultrasonic sensors. For example, one ultrasonic sensor may be positionedwithin the housing of the system to detect ultrasonic events whenmounted to a ceiling and the other sensor may be positioned within thehouse to detect ultrasonic events when mounted to a wall. Smoke detector324 can be one of the safety sensors (as previously discussed). Displaymodule 328 can be any suitable display apparatus. In one embodiment,display module 328 can include one or more LEDs that emit differentcolored light to signify a status of system 300. For example, display ofgreen light can signify good status, orange light can signify a warningcondition such as a low battery, and red light can signify a hazardcondition. Each of the components power bus 308 is coupled to receive DCpower at the first voltage level. Although ultrasonic sensor 320, smokedetector 324, and display module 328 can operate using DC power at thefirst voltage level, other components in system 300 can requiredifferent operating voltages. In addition, it is understood thatalthough various components such as ultrasonic sensor 320, smokedetector 324, and display module 328 can receive power from power bus308 at a first voltage level, one or more of these components may haveinternal power conversion circuitry. For example, ultrasonic sensor 320and display module 328 can each include a boost converter.

Power converter circuitry 340, 342, 344, and 346 are each operative toconvert the DC power signal provided on power bus 308 to a signal havinga different voltage level. Power converter circuitry 340, 342, and 344can all be operative to down convert the DC power signal to threedifferent voltage levels lower than the first voltage level. Moreparticularly, power converter circuitry 340 can be a buck converter thatprovides a signal having a second voltage level (e.g., 1.8 volts) topower bus 341. Power bus 341 is coupled to system processor 310 (e.g.,which can be similar to processor 210 of FIG. 2), safety processor 330,6LoWPAN module 314 (e.g., which can be similar to low power wirelesscommunication circuitry 214 of FIG. 2) via power gating circuitry 361,WiFi module 312 (e.g., which can be similar to high power wirelesscommunication circuitry 212 of FIG. 2) via power gating circuitry 363,and non-volatile memory 316 (e.g., which can be similar to non-volatilememory 216) via power gating circuitry 365.

Some of the sensors may include subcomponents that have separate powerrequirements, and as such, may need to be separately powered. Suchsensors may be coupled to receive power from two or more power busses sothat the subcomponents are supplied with the appropriate power. In someembodiments, one or more of the subcomponents of a sensor may be powergated ON and OFF. For example, smoke detector 324 can be an activesensor that “interrogates” air contained within a chamber with an activeIR signal, and then measures the IR signal to see how much of thatsignal is scattered. Thus, in some embodiments, smoke detector 324 caninclude a smoke detection optical source (a first subcomponent) and asmoke detection optical sensor (a second subcomponent), with each ofthese components being separately powered. In particular, power bus 308can provide power to the smoke detection optical source and power bus343 can provide power to the smoke detection optical sensor via powergating circuitry 354. During operation of hazard detection system 300,the smoke detection optical sensor may be selectively powered viacontrolled coupling and de-coupling to power bus 343 by power gatingcircuitry 354. Although the smoke detection optical source is coupled topower bus 308, it may be turned ON and OFF in response to a drivingsignal (e.g., provided by safety processor 330). Thus, in thisembodiment, power savings can be achieved by (1) signal driving thesmoke detection optical source and by (2) power gating the smokedetection optical sensor.

As another example, ultrasonic sensor 320 can include a transmit/boostsubcomponent and a transducer subcomponent, with each of thesesubcomponents being separately powered. The transmit/boost component maybe coupled to receive power from power bus 308 and the transducersubcomponent may be coupled to receive power from power bus 349 viapower gating circuitry 364. During operation of hazard detection system300, for example, the transducer subcomponent may be power gated ON andOFF via power gating circuitry 364 and the transmit/boost subcomponentmay be signal driven ON and OFF. Thus, although the transmit/boostsubcomponent can be directly coupled to power bus 308, thetransmit/boost subcomponent may not be turned ON unless it is signaldriven ON (e.g., by a signal provided by system processor 310), therebyminimizing power consumption. Thus, power consumption by ultrasonicsensor 320 can be minimized using two different approaches: power gatingand signal driving. It is understood that other sensors may utilizesimilar approaches to minimize power consumption and extend batterylife. It is further understood that some sensors may not includesubcomponents that are coupled to power gating circuitry, but suchsubcomponents can be turned ON and OFF via signal driving.

Power converter circuitry 342 can be a buck converter that provides asignal having a third voltage level (e.g., 3.0 volts) to power bus 343.Power bus 343 is coupled to RF Front-End Module (FEM) 315 via powergating circuitry 362, ultrasonic sensor 320 via power gating circuitry364, both ALS sensor 322 and temperature and humidity sensor 323 viapower gating circuitry 355, and low-drop out regulator 348. Ultrasonicsensor 320 receives power on power busses 308 and 343. RF FEM 315operates in connection with 6LoWPAN module 314 and can include a poweramplifier (PA) for transmitting data, a low-noise amplifier (LNA) forreceiving data, an optional antenna switch, and an optionaltransmit/receive switch. The PA boosts the power of the transmittingsignal to improve signal range and the LNA improves sensitivity whenreceiving a signal. 6LoWPAN module 314 can optionally leverage FEM 315to improve its performance, but doing so incurs a power penalty. ALSsensor 322 and temperature and humidity sensor 323 can be similar tosafety sensors 232 discussed above in connection with FIG. 2.

Power converter circuitry 344 can be a buck converter that provides asignal having a fourth voltage level (e.g., 3.3 volts) to power bus 345.Power converting circuitry 344 can be operative to be selectively turnedON and OFF, depending on a signal applied to node 368. The signalapplied to node 368 can be provided by system processor 310. Power bus345 can be coupled to WiFi module 312 and speaker 318. Speaker 318 canbe similar to speaker 218 (discussed above in connection with FIG. 2).The fourth voltage level can be higher than the third voltage level.Even though WiFi module 312 and speaker 318 could operate using thethird voltage level, use of the fourth voltage level results in aperformance boost. The increased operating voltage can increase thewireless range of WiFi module 312 and increase the loudness of speaker318. In some embodiments, power converter circuitry 344 can be omittedand WiFi module 312 and speaker 318 can be coupled to power bus 343.WiFi module 312 is coupled to power bus 341 via gating circuitry 363 toreceive power for its digital circuitry, logic, and to communicate withsystem processor 310 and is coupled to power bus 345 to receive powerfor its radio and transceiver. Thus, as shown, WiFi module 312 can haveits digital logic circuitry power gated ON and OFF by gating circuitry363, and its radio and transceiver can be powered ON and OFF dependingon whether power converter circuitry 344 is turn ON.

Power converting circuitry 346 can be operative to up convert the DCpower signal to a voltage level higher than the first voltage level.Power converting circuitry 346 can be operative to be selectively turnedON and OFF, depending on a signal applied to node 358. Power convertingcircuitry 346 can be a boost converter that provides a signal having afifth voltage (e.g., 12 volts) to power bus 347. Alarm 334 can besimilar to alarm 234 (discussed above in connection with FIG. 2).

It is understood that although power converting circuitry 340, 342, 344,346 were described above as having either a buck converting topology orboost converting topology, any suitable converting topologies can beused. For example, other DC-DC converting topologies such as buck-boostcan be used. In addition, converting topologies that use transformerscan be used, such as, for example, full-bridge forward converters, halfbridge forward converters, single-ended converters, push pullconverters, and clamp converters.

Low-dropout regulator 348 is operative to provide “high” quality,stable, power to power bus 349. Low-dropout regulator 348 can change thevoltage level of the signal it receives on power bus 343 to provide asixth voltage level to power bus 349. The quality of the signal on powerbus 349 is higher than the quality of the signal on power bus 343.Signal quality can be measured by any number of differentcharacteristics. A few characteristics include voltage ripple,deviations from an average voltage level, transient response, and noise.

In an explanation by way of example, assume that power convertingcircuitry 342 is operative to provide a signal having the third voltagelevel (e.g., 3.0 volts) to power bus 343 and regulator 348 changes thethird voltage level to the sixth voltage level (e.g., 2.7 volts). Duringoperation of system 300, power demands on power bus 343 may temporarilydisrupt power converter circuitry 342's ability to provide a signal atthe third voltage level. For example, if ultrasonic sensor 320 is turnedON, the current demanded by sensor 320 could cause the voltage of thesignal provided to power bus 343 to momentarily drop below the thirdvoltage level. Despite this drop in voltage level, regulator 348 isoperative to maintain its output signal at the sixth voltage level,thereby ensuring all components coupled to power bus 349 continue tooperate unaffected by changes in the signal on power bus 343.

Power bus 349 can be coupled to smoke detector 324 via power gatingcircuitry 354, CO sensor 325, and PIR sensor 327. CO sensor 325 can beone of the safety sensors 232 discussed above in connection with FIG. 2.CO sensor 325 may use an electrochemical sensor to detect CO gas. Thisparticular type of sensor requires a relatively stable signal tofunction properly and it is also the type of sensor that must always bereceiving power. The constant power requirement may be necessary becauseit takes too long for the sensor to stabilize and take accurate COreadings if power gated ON and OFF. CO sensor 325 receives a stablepower signal from regulator 348 on power bus 349 and is not power gated,thereby operative to always receive power from power bus 349. PIR sensor327 is another type of sensor that requires a relatively stable signalto function properly and must always be receiving power.

Smoke detector 324 is coupled to power busses 308 and 349. Power bus 308powers an infrared (IR) LED and power bus 359 powers receiver and signalamplification circuitry. In some embodiments, power bus 308 can supplypower to the IR LED (e.g., smoke detector optical source) through anadjustable LDO (not shown). This LDO can be selectively enabled bysafety processor 330, and is only toggled when an LED pulse is required;safety processor 330 can provide a driving signal to the smoke detectoroptical source (to turn it ON and OFF) and it can also control operationof power gating circuitry 354 to selectively power the receiver andsignal amplification circuitry. When an IR LED pulse is not required,the LDO is disabled, and power gating circuitry 354 decouples power bus359 to the receiver and signal amplification circuitry (e.g., smokedetector optical detector). As result, when the LDO is disabled andpower gating circuitry 354 is OPEN, smoke detector 324 can have aminimal current draw (e.g., less than 1 μA).

System 300 can include one or more thermistors 326 situated in variouslocations within system 300. Thermistors 326 can be another one of thesafety sensors as previously discussed in connection with FIG. 2. Asshown, thermistors 326 are NTC type thermistors, though it is understoodthat other types of thermistors can be used. Thermistors 326 are coupledto safety processor 330 via power bus 331. Safety processor 330 canselectively provide a power signal to power bus 331. For example, whensafety processor 330 desires to take temperature readings fromthermistor 326, it can provide power to power bus 331. After the readingis taken, processor 330 can shut off the power to power bus 331. Inanother embodiment, processor 330 can constantly supply power to powerbus 331.

The various components and power busses of hazard detection system 300can reside on one or more printed circuit boards or flexible printedcircuit boards. In one embodiment, PIR sensor 327 and display module 328can reside on flexible printed circuit board 329 and all othercomponents can reside on a printed circuit board (not shown). In anotherembodiment, all components can reside on a printed circuit board.

FIG. 3 shows a dashed line 370 snaking between various components ofsystem 300. Dashed line 370 demarcates an illustrative divide ofcomponents dedicated to providing 1) safety features and 2) enhancedfeatures, and in particular, generally shows how power is managed byprocessors 310 and 330. Components generally associated with safetyfeatures are shown below dashed line 370 and components generallyassociated with enhanced features are shown above dashed line 370.Dashed line 370 further serves to illustrate the bifurcated processorsembodiment in which safety processor 330 is dedicated to safety featuresand system processor 310 is dedicated to handling enhanced features aswell as general system administration. As will be discussed in moredetail below, dashed line shows that safety processor 330 manages powerconsumption of the “safety” components and system processor managespower consumption of the other components.

The safety features of system 300 are robust, power efficient, andoperate without fail. To ensure the robust and power efficient use ofthe safety features, system 300 can operate as follows. Power convertingcircuitry 340 and 342 can be operative to always be ON (at least duringintended and ordinary usage of system 300) throughout its minimumoperational lifespan. There may be instances in which power convertingcircuitry 340 and 342 are not always ON, such as when the system 300undergoes a full power-cycle reset. This way, power supplied on powerbusses 341 and 343 is always available to downstream components. Thesecomponents can include system processor 310, safety processor 330,non-volatile memory 316, low-dropout regulator 348, and the safetysensors (e.g., ALS sensor 322, temperature and humidity sensor 323,smoke detector 324, CO sensor 325, thermistors 326, and PIR sensor 327).That safety processor 330 and the safety sensors have access to powervia always ON power converting circuitry 340 and 342 ensures that system300 is constantly monitoring for hazard events.

Power savings can be realized because safety processor 330, as opposedto system processor 310, is dedicated to monitoring the safety sensorsfor a hazard condition. Additional power savings can be realized bypower gating various components. In particular, safety processor 330 canindependently control each of power gating circuits 353, 354, and 355.Thus, processor 330 can selectively couple and de-couple display module328 to power bus 308, smoke detector 324 to power bus 349, and both ALSsensor 322 and temperature and humidity sensor 323 to power bus 353 bycontrolling power gating circuits 353, 354, and 355, respectively. Sincedisplay module 328, smoke detector 324, and both ALS sensor 322 andtemperature and humidity sensor 323 can operate properly even when beingfully turned ON and OFF, system 300 can further manage power consumptionby selectively disconnecting them from their respective power busses.Further still, processor 330 can extract additional power savings byselectively providing power to power bus 331.

Safety processor 330 can further manage power consumption by selectivelyenabling power converting circuitry 346. Processor 330 can enable ordisable circuitry 346 by applying the appropriate signal to control node358. When converting circuitry 346 is enabled, it can provide a signalat the fifth voltage level to power bus 347. Processor 330 can enablecircuitry 346 when a hazard event is detected, and once circuitry 346 isenabled, alarm 334 is operative to sounds its alarm. When no hazardevent is detected or there is no need for alarm 334 to be active,processor 330 can disable circuitry 346. Disabling circuitry 346 savespower lost during the operation of circuitry 346 and as well as powerthat would otherwise be consumed by alarm 334.

Power management can also be exercised by processor 310. Processor 310can independently control each of power gating circuits 361, 362, 363,364, and 365. Thus, processor 310 can selectively couple and de-couple6loWPAN module 314 to power bus 341, FEM 315 to power bus 343, WiFimodule 312 to power bus 341, non-volatile memory 316 to power bus 341,and ultrasonic sensor 320 to power bus 343 by controlling power gatingcircuits 361, 362, 363, 364, and 365, respectively. These power-gatingcompatible components can be completely disconnected from a power busand still be able to function properly when re-connected to theirrespective power busses.

System processor 310 can further manage power consumption by selectivelyenabling power converting circuitry 344. Processor 310 can enable ordisable circuitry 344 by applying the appropriate signal to control node368. When converting circuitry 344 is enabled, it can provide a signalat the fourth voltage level to power bus 345. Processor 310 can enablecircuitry 344 when WiFi module 312 and speaker 318 require power.Disabling circuitry 344 saves power lost during the operation ofcircuitry 344 and as well as power that would otherwise be consumed byWiFi module 312 and speaker 318.

System processor 310 and safety processor 330 can operate according toseveral different power modes. For example, in a very simplistic sense,both processors 310 and 330 can operate in an active mode and a sleepmode. As another example, one or more of processor 310 and 330 can havemultiple active modes and multiple sleep modes, each having a differentpower consumption level. The particular mode each processor operates inmay depend on the mode operation of the system 300. For example, ifsystem 300 is in an Idle mode of operation, system processor 310 may bea relatively deep sleep mode, and safety processor 330 may be in arelatively low power active mode.

Although system 300 is shown and described to include battery system301, it is understood that battery system 301 can be replaced with aline powered power supply. For example, the line powered power supplycan include an AC-to-DC converter, among other circuitry, to convert anAC signal to a DC signal that is provided to bus 308. Additional detailsof a line-powered hazard detection system can be found, for example, incommonly assigned, U.S. Pat. No. 9,958,885, the disclosure of which isincorporated by reference herein in its entirety.

FIGS. 4A-4D show different views of input processing detection system400 along with its illustrative positioning of several sensors inaccordance with various embodiments. In particular, FIG. 4A shows a topview of system 400, FIG. 4B shows a side view of system 400, FIG. 4Cshows a cross-sectional view of system 400 taken along line C-C of FIG.4A, and FIG. 4D shows a cross-sectional view of system 400 taken alongline D-D of FIG. 4A. A top portion of detection system 400 is shownfacing up out of the page in FIG. 4A, but the top portion of system 400is shown facing in a downward fashion (which is how it would face ifmounted to a ceiling). FIG. 4A shows that detection system 400 includesfour sensors located at different locations in or on a housing. In oneembodiment, the sensors can include PIR sensor 410, ultrasonic sensor420, ultrasonic sensor 422, button 440, and an ambient light sensor (notshown). PIR sensor 410 and ultrasonic sensor 420 can be located in arelatively centered location within system 400. Both sensors 410 and 420are also positioned at or near the top surface of system 400, and insome embodiments may extend beyond a plane that defines the top surface.For example, as illustrated in FIG. 4C, PIR sensor 410 may extend beyondthe top surface plane. As another example, as illustrated in FIG. 4D,ultrasonic sensor 420 may be positioned substantially co-planer with thetop surface.

Ultrasonic sensor 422 can be positioned near an edge of system 400 (asshown) or elsewhere on system 400. For example, sensor 422 can bepositioned adjacent to sensor 422. Similar to sensor 420, sensor 422 mayalso be positioned at or near the top surface of system 400, and in someembodiments may extend beyond a plane that defines the top surface. Forexample, as shown in FIG. 4B, sensor 422 may be positioned substantiallyco-planer with the top surface. Button 440 can be positioned anywhere onhazard system 400 such that a user can depress it. For example, as shownin FIG. 4A, button 440 can be recessed within a boundary of hazardsystem 400.

FIG. 4E shows an illustrative cross-sectional view of hazard system 400taken along line E-E of FIG. 4A. This view shows sensors 410, 420, and422 and the respective detection fields 411, 421, and 423. Detectionfields 411, 421, and 423 illustrate each sensor's “field of view” fordetecting one or more stationary or moving objects. The size and shapeof each sensor's “field of view” can be different. For example, PIRsensor 410 can have a relatively omnipresent detection field andultrasonic sensors 420 and 422 can have relatively focused detectionfields. In one embodiment, detection field 411 can encompass bothdetection fields 421 and 423. Detection fields 421 and 423 may or maynot overlap each other, but each field can be configured to monitor adifferent field of view. For example, detection field 421 can becentered on an axis that is perpendicular to the top surface of hazardsystem 400, and detection field 423 can be centered on an axis that isnot perpendicular to the top surface of hazard system 400. In anotherexample, the center axes of detection field 421 and detection field 423are not parallel to each other. During operation, ultrasonic sensors 420and 422 can be alternately sampled to avoid interference among detectionfields 421 and 423.

The combined use of ultrasonic and infrared sensors enables anultrasound-plus-IR detection methodology for discerning whether one ormore objects are actually present within a particular field of view andfor processing inputs received while the one or more objects are presentwithin that field of view. As will be illustrated and discussed in moredetail below in connection with FIGS. 5A and 5B, the ultrasonic sensorprovides a relatively focused field of view by emitting high frequencysound waves and monitoring for echoes that are received back from anyobjects within its field of view, and the infrared sensor provides arelatively unfocused field of view, which can encompass all or a portionof the ultrasonic sensor's field of view, by monitoring energy beingemitted from objects in its field of view. Thus, even though bothsensors can detect objects, the disparate nature of the sensors enablesthe detection methodology to discriminate among different moving objectsand process inputs with a relatively high degree of accuracy. Inparticular, the ultrasonic sensor can provide “presence” detection andthe infrared sensor can provide “input processing” detection. While theinfrared sensor can detect movement of one or more objects anywherewithin its field of view, the detection methodology can decide whetherto process an infrared detected moving object as an “input” based onwhether the ultrasonic sensor senses the “presence” of that movingobject. Thus, in one embodiment, the detection methodology canselectively filter out infrared detected moving objects if theultrasonic sensor does not detect the presence of the moving object.This can reduce or completely eliminate false positives. For example,the infrared sensor may detect movement of an object within its field ofview, but if that same object is not detected by the ultrasonic sensor,the detection methodology can ignore that detected moving object and notprocess it as an input. As another example, if the infrared sensordetects movement of an object, and that same object is detected by theultrasonic sensor, the detection methodology may process it as an input

The ultrasound-plus-IR detection methodology can be used in manydifferent applications. In some embodiments, the detection methodologyaccording to various embodiments can be used to process inputs inresponse to one or more objects moving relatively far away (e.g., a fewmeters) from the input processing system. In other embodiments, thedetection methodology can be used to process inputs in response to oneor more objects moving relatively close (e.g., a few feet) to the inputprocessing system. Regardless of the proximity of the moving objects,the input processing system can recognize different movement patterns orgestures. Each recognized movement pattern may cause a particular actionto be performed. It is understood that the particular action takendepends on the design of system using the ultrasound-plus-IR detectionmethodology. In a personal computing system, for example, an up and downmovement pattern may correspond to a scrolling UI interface action. Asanother personal computing example, a left to right movement pattern maycorrespond to a page turning UI interface action. In a hazard detectionsystem, for example, a waving motion pattern may correspond to a silencethe alarm interface action. A stereo system, for example, may adjust thevolume responsive to the relative distance between two hands; as thedistance between the hands increases, the volume increases.

The ultrasound-plus-IR detection methodology is a specific example of aultrasound-plus-radiation detection methodology according to embodimentsherein. Ultrasound-plus-radiation detection methodologies can use anultrasonic sensor and another sensor that monitors any type ofradiation, particularly, non-ionizing radiation. Other embodiments thatleverage ultrasonic sensors can incorporate use of an optical sensor(e.g., camera). Such embodiments can employ the ultrasound-plus-imagedetection methodology, where the ultrasonic sensor is used for presencedetection, and the image is used for processing inputs.

Even though various embodiments discussed herein use an ultrasonicsensor for “presence” detection and a PIR sensor for “input processing”detection, it is understood that different sensors may be used forperforming presence detection and input processing detection. Forexample, the following can be used for presence detection: thermopilesensor, carbon dioxide sensor, Laser/IR LED proximity sensor (formeasuring reflected light intensity), Laser/IR LED time-of-flight sensor(for measuring time for light to bounce off target and come back),ultrasonic sensor (for measuring reflected sound), ultrasonic sensor(for measuring Doppler shift), a camera, radar, and radio frequency. Forexample, the following can be used to detection motion: PIR sensor,multi-pixel thermopile, single or multiple Laser/IR LED proximitysensors, single or multiple Laser/IR LED time-of-flight sensors,ultrasonic (reflected sound), ultrasonic (Doppler shift), single ormultiple cameras, radar, and radio frequency.

Referring collectively now to FIGS. 5A and 5B, illustrative detectionfields emanating from sensors (not shown) of hazard detection system 500are shown in accordance with various embodiments. In particular, FIG. 5Ahazard detection system 500 is mounted to ceiling 512 of enclosure 510,and FIG. 5B hazard detection system 500 is mounted to wall 514 ofenclosure 510 are shown in accordance with an embodiment. Hazarddetection system 500 can be the same for both FIGS. 5A and 5B, and thusvarious aspects described in connection with one FIG. can apply to theother FIG. For example, the detection fields and their respective fieldof view angles and center axis positions can be the same for both FIGS.The main difference between FIG. 5A and FIG. 5B is where hazarddetection system 500 is mounted. In FIG. 5A, it is mounted to a ceiling(or other object that is substantially parallel to the ground), and inFIG. 5B, it is mounted to a wall (or other object that is substantiallyperpendicular to the ground). Enclosure 500 can include ceiling 512,walls 514 and 516, and floor 518.

Three different detection fields are shown: PIR detection field 520,ultrasonic detection field 530, and ultrasonic detection field 540. Eachdetection field shows a series of dashed lines that represent eachfield's outer bounds. PIR detection field 520 can stem from a PIR sensor(not shown), and ultrasonic detection fields 530 and 540 can stem fromultrasonic sensors (not shown). Although the fields appear to betwo-dimensional, it is understood that the fields occupy athree-dimensional space. As shown, PIR detection field 520 can occupy avast majority of enclosure 510 due to its relatively large, wide anglefield of view. In particular, PIR detection field 520 can have field ofview angle, A, as shown. Ultrasonic detection fields 530 and 540 caneach occupy a minority of enclosure 510 due to their relatively small,narrow angle fields of view. In particular, detection fields 530 and 540can have field of view angles, B1 and C1, respectively as shown. Thevalue of angle A can be greater than the values of angles B1 and C1. Thevalues of angles B1 and C1 can be the same or different.

Detection fields 530 and 540 are shown with respective center axes 531and 541. Detection field 520 can have a center axis, but it is not shownto avoid overcrowding the FIG. In some embodiments, the center axes ofdetection fields 520 and 530 can be co-planer or co-axial, but thecenter axes of detection fields 530 and 540 are neither co-planer norco-axial. The positions of the center axes with respect to referenceplane 501 vary. As shown, an angle of B2 exists between center axis 531and reference plane 501, and an angle of C2 exists between center axis541 and reference plane 501. Angle B2 can be greater than angle C2.

The value of angles B2 and C2 can be selected to maximize the potentialfor the ultrasonic sensors (not shown) to detect the presence of one ormore moving or stationary objects, regardless of how hazard detectionsystem 500 is mounted. For example, angle B2, for detection field 530,can be selected for ceiling mounted applications, and angle C2, fordetection field 540, can be selected for wall mounted applications.Continuing with this example, angle B2 can range from 80-100 degrees,and angle C2 can range from 5 to 80 degrees. It is understood that anysuitable angle can be selected for angles B2 and C2, respectively. Forexample, in one embodiment angle B2 can range from 90 to 180 degrees andangle C2 can range from 0 to 90 degrees. As a specific example of thisembodiment, angle C2 can be 45 degrees and angle B2 can be 135 degrees.

As shown in FIG. 5B, center axis 531 is substantially perpendicular towall 514, and as a result detection field 530 projects in a directionsubstantially perpendicular to wall 514. In some embodiments, dependingon the height at which system 500 is mounted, detection field 530 maynot be ideally suited for detecting an object (e.g., a person attemptingto gesture hush an audible alarm). This may be because the person is nottall enough to reach detection field 530. Detection field 540, which isdirected downwards towards floor 518, may be better suited for detectingthe object. This may be because the person will eventually enterdetection field 540 regardless of how tall he or she is. Thus, in wallmounted applications, objects detected in detection field 540 may takeprecedence over any objects detected in detection field 530.

In contrast, in ceiling mounted applications (FIG. 5A), objects detectedin detection field 530 may take precedence over objects detected indetection field 540. As shown, center axis 531 is substantiallyperpendicular to ceiling 518, and as a result detection field 530projects directly towards floor 518, regardless of how high the ceilingis with respect to the floor. Detection field 540 is also directeddownwards to the floor, but not as directly as detection field 530. Insome embodiments, depending on ceiling height, detection field 540 maybe cast too far away from hazard detection system 500 to effectivelydetect an object (e.g., a person attempting to gesture hush an audiblealarm). Thus, detection field 530 may be better suited for detecting anobject in ceiling mounted applications.

In some embodiments, hazard detection system 500 can selectively enableand disable one or more of its ultrasonic sensors. For example, system500 can disable an ultrasonic sensor based on how it is mounted. System500 can have an orientation sensor contained therein such as, forexample, a multi-axis accelerometer, for determining its mountedorientation. If system 500 is wall mounted, it can disable the sensorcasting detection field 530. If system 500 is ceiling mounted, it candisable the sensor casting detection field 540.

In one embodiment, angles B2 and C2 are permanently fixed. In anotherembodiment, one or more of angles B2 and C2 are adjustable. For example,one or more of the ultrasonic sensors (not shown) can be pivoted about arotation axis to change the angle of its central axis with respect toreference plane 501. In one embodiment, a user can manually pivot anultrasonic sensor. In another embodiment, hazard system 500 can controlthe pivot position of one or more ultrasonic sensors. For example, thesensor can be mounted on a motor controlled gimbal platform. The abilityto change the center axis angle can be particularly advantageous toaccommodate wall mounts of varying heights. For example, the hazarddetection system can adjust the center axis angle of a detection fieldbased on the mount height.

FIGS. 6A-6D show illustrative snapshots in time in which a person uses agesture to silence an audible alarm in accordance with an embodiment,and FIG. 7 shows an illustrative timing diagram of various components ofa hazard detection system in accordance with an embodiment. Thesnapshots of FIGS. 6A-6D can correspond to times, t₁-t₄, respectively,of FIG. 7. Any suitable hazard detection system in accordance with anembodiment can be used, but for convenience and ease of discussion,hazard detection system 500 of FIG. 5A is referenced in connection withFIGS. 6A-6D and FIG. 7. Accordingly, as already discussed above, system500 can cast detection fields 520, 530, and 540 as shown. In addition,the hazard detection system can include, among other components, a PIRsensor, two ultrasonic sensors, an alarm, a speaker, and one or morehazard detection sensors.

FIG. 7 shows timing waveforms for alarm event 702, PIR sensor samplerate 704, ultrasonic sensor enable 705, first ultrasonic sensor objectdetection waveform 706, second ultrasonic sensor object detectionwaveform 708, PIR gesture detection waveform 710, speaker output 712,and audible alarm output 714. Alarm event 702 can indicate whether thehazard detection system senses a condition that triggers an alarm event.For example, if the hazard detection system senses smoke, alarm event702 can transition from low to high (as it does at time t₁). PIR samplerate 704 indicates the rate at which PIR data is sampled. Ultrasonicsensor enable 705 indicates whether the ultrasonic sensors are enabled.For example, the ultrasonic sensors can be power gated off when not inuse. Ultrasonic sensor object detection waveforms 706 and 708 canindicate whether an ultrasonic sensor detects an object. Waveform 706can correspond to objects detected in detection field 540, and waveform708 can correspond to objects detected in detection field 530. PIRgesture detection waveform indicates whether a gesture is recognizedwithin detection field 520. Speaker output 712 indicates whether thespeaker is playing back a message, and audible alarm output 714indicates whether the alarm is sounding.

Between times, t₀ and t₁, the waveforms for alarm event 702, ultrasonicsensor enable 705, first and second ultrasonic sensor detectionwaveforms 706 and 708, PIR gesture detection waveform 710, speakeroutput 712, and audible alarm output 714 are all LOW. In this state, theultrasonic sensors can be power gated off. For example, power gatingcircuitry 364 can be OPEN so that ultrasonic sensors 320 are OFF. Inaddition, PIR sample rate 704 is set at a first sample rate. At time,t₁, alarm event 702 goes HIGH, which can cause the alarm to sound.Audible alarm output 714 goes HIGH at time, t₁. Ultrasonic sensor enable705 goes HIGH, thereby powering ON the ultrasonic sensors. In addition,PIR sample rate 704 may change from the first sample rate to a secondsample rate, where the second sample rate has a higher frequency thanthe first. In FIG. 6A, hazard detection system 500 is sounding its alarmas indicated by the “buzz, buzz, buzz” emanating therefrom. Person 600is shown at location 601, which is within detection field 520 butoutside of detection fields 530 and 540.

At time, t₂, person 600 moves from location 601 to location 602, whichis within detection field 520 but outside of detection fields 530 and540. Because person 600 is moving within detection field 520, themovement may be detected by the PIR sensor. This is shown as the stepchange in PIR gesture detection waveform 710 at time, t₂. Even thoughthe PIR sensor detects a gesture (e.g., movement of person 600) withindetection field 520 this does not silence the alarm.

At time, t₃, person 600 moves from location 602 to location 603, whichis within detection fields 520 and 530 but not within detection field540. Now that person 600 is within detection field 530, the ultrasonicsensor monitoring that field may sense the presence of person 600. Thisis shown in ultrasonic sensor object detection waveform 708, whichtransitions from LOW to HIGH at time, t₃. In addition, in response toone of the ultrasonic sensors detecting an object, the speaker mayplayback a message. As shown in FIG. 6C, the message is “wave to hushalarm.” Any suitable message can be played back, in any language. Thebeginning of the speaker message playback is shown in FIG. 7 as speakeroutput 712 transitions from LOW to HIGH at time, t₃. In addition to, orin place of, the audio message, a visual indicator (e.g., LED 328 ofFIG. 3), not shown, may be presented when person 600 is detected aspresent within detection field 530. The visual indicator may light up orrapidly blink when person 600 is within detection field 530. The audioand/or visual indicator can inform the occupant that the hazarddetection system is ready to detect and process any gestures that theoccupant may perform. Moreover, the audio and/or visual indicator mayprovide useful feedback to the occupant so that occupant knows when toperform gesture motions (e.g., because if the occupant performs agesture outside of detection field 530 or detection field 540, thehazard detection system may ignore the occupant's gesture).

At time, t₄, person 600 can wave one or more arms while in position 603.In response to detecting the gesture, the hazard detection system cansilence the audible alarm. In FIG. 6D, the “buzz, buzz, buzz” sound isgone. In FIG. 7, PIR gesture detection waveform 710 shows that a gestureis detected at time, t₄. The simultaneous detection of the gesture bythe PIR sensor and the presence of person 600 within ultrasonicdetection field 530 can cause the hazard detection system to silence itsalarm. This is shown at time, t₄, when audible alarm output 714transitions from HIGH to LOW. Alarm event 702 is still HIGH at time, t₄,thus the alarm may sound again after a predetermined period of timeelapses and alarm event 702 is still HIGH. In addition, if desired, avisual indicator may be presented to indicate that the alarm has beenhushed. Moreover, if further desired, an audible message may be playedback to indicate that the alarm has been hushed. The audible message canspecify which alarm is hushed. For example, if the alarm is a smokealarm, the audible message can specify that the smoke alarm has beenhushed. As another example, if the alarm is a self-test, the audiblemessage can specify that the self-test has been hushed. In addition, theaudible message can specify for how long the alarm will be hushed. Forexample, the audible message may say that “The smoke alarm will besilent for five minutes.”

FIG. 8 shows an illustrative detection field for PIR sensor 800 inaccordance with an embodiment. PIR sensor 800 can cast multiplesubfields 810 a-i to define detection field 802 and can provide anoutput in the form of raw data when the object moves from one subfieldto another. For example, if an object moves from subfield 810 e tosubfield 810 f, sensor 800 will detect the movement of the objectprovide it as part of its raw data output. The raw data outputted bysensor 800 may not correspond to an actual physical measurement (e.g.,Joules), but may correspond to a combined infrared delta seen bysubfields 810 a-i within a given time window. Detected movement of anobject from one subfield to another subfield contributes to an infrareddelta. Thus, if there are several objects passing from one field toanother, each of these detected movements can contribute to the combinedinfrared delta. If, however, an object does not move and stays perfectlystill within one subfield, sensor 800 may not detect movement of theobject, and the infrared delta can effectively be zero. In someembodiments, the raw data output may be filtered to eliminate ambientinfrared noise. For example, the raw data output of PIR sensor 800 maybe filtered by a low-pass Butterworth filter with a cutoff frequency at3 Hz. Illustrative examples of filtered PIR outputs are shown in FIGS.9A-9D.

Referring now to FIGS. 9A-9D, several different illustrative graphsshowing PIR sensor data are shown. In order for a gesture detectionalgorithm according to various embodiments to ascertain whether agesture event is being detected, the continuous raw data received fromthe PIR sensor or the filtered PIR data may be processed by asegmentation algorithm. The segmentation algorithm ascertains amplitudeand period statistics of detected motion, and it may be these statisticsthat are used by a gesture detection algorithm to determine whether agesture event motion has been detected. Each graph shows magnitude ofthe combined infrared delta versus time. The magnitude can be a functionof how much mass is detected moving from one subfield to another, andthe frequency of detected motion can be a function of how fast theobject is moving. FIG. 9A illustrates a graph in which no movement isbeing detected by a PIR sensor. As shown, waveform 910 is flat. FIG. 9Billustrates waveform 920, which can represent one mass unit (e.g., onearm) moving at a “normal” speed. As shown, waveform 920 has period T,and amplitude A. FIG. 9C illustrates waveform 930, which can representone mass unit moving at a “slow” speed. As shown, waveform 930 hasperiod ½ T and amplitude A. FIG. 9D illustrates waveform 940, which canrepresent two mass units (e.g., two arms) moving at “normal” speed. Asshown, waveform 940 has an amplitude of 2A (e.g., which is twice that ofthe amplitude generated by a single mass unit) and a period of T.

FIG. 10 shows illustrative waveforms of raw and filtered PIR data inaccordance with an embodiment. The x-axis shows a sample number and they-axis shows energy delta measured by the PIR sensor. Waveform 1010 maybe a raw PIR data waveform and waveform 1020 may be a filtered PIR datawaveform. Waveform 1020 can include inflection points 1021, 1022, 1023,and 1024. An inflection point can occur when the slope of a waveformchanges from positive to negative or from negative to positive. Theinflection points shown in FIG. 10 exist when the slope of waveform 1020changes from positive to negative. As will be discussed in more detailbelow, the inflection points can define the boundaries of detectedmotion events (e.g., a detected wave motion). As shown, waveform 1020includes detection motion event 1030, which is bounded by inflectionpoints 1021 and 1022, detected motion event 1040, which is bounded byinflection points 1022 and 1023, and detected motion event 1050, whichis bounded by inflection points 1023 and 1024. The period and amplitudestatistics of each detected motion event can be determined by applying asegmentation process. The pseudo-code for such a process can berepresented by:

-   1. Obtain last three filtered PIR sensor data values;-   2. Determine whether an inflection point exist in the filtered data    values;-   3. If an inflection point exists, then    -   a. if a prior inflection point has been observed, then        -   i. Let t_(period)=t_(current)−t_(begin)        -   ii. Let y_(amplitude)=y_(max)−y_(min)    -   b. Reset y_(min) and y_(max) to a current filtered PIR sensor        value    -   c. Set t_(begin) to t_(current)-   4. If the current filtered PIR sensor value is less than y_(min),    then set y_(min) to the current filtered PIR sensor value-   5. If the current filtered PIR sensor value is more than y_(max),    then set y_(max) to the current filtered PIR sensor value    where t_(period) is the period of the detected motion event,    t_(current) is the time corresponding to the inflection point    detected in the last three filtered PIR sensor data values, and    t_(begin) is the time corresponding to the prior inflection point.    Y_(amplitude) is the amplitude of the detected motion event, y_(min)    is the minimum amplitude value observed within the detected motion    event and y_(max)is the maximum amplitude value observed within the    detected motion event.

FIG. 11 shows an illustrative state machine 1100 for calibratingdetection sensors and for detecting a motion event according to anembodiment of the invention. For ease of discussion, the right hand sideof the FIG. generally refers to the calibration aspect of state machine1100 and the left hand side generally refers to the motion detectionaspect of state machine 1100. During discussion state machine 1100,reference will be made to FIGS. 12 and 13 to aid in the description ofvarious embodiments. State machine 1100 can be implemented in anysuitable system such as a personal computing device, a security system,or a hazard detection system. The system operates according to itsdesign criteria and from time to time, may cause state machine 1100 tochange states. When the system does not require any action of statemachine 1100, state machine 1100 is in OFF state 1102, which canrepresent a state in which the sensors are not being used to detect amotion event and are not being calibrated. In some embodiments, statemachine 1100 is preferably in OFF state 1102 the majority of itsoperational life to minimize power consumption.

In order for gestures to be recognized, the system may require acalibration. The calibration can define a baseline from which variousdetectors can accurately interpret data being received from one or moresensors. In one embodiment, in order to determine presence of an objectand the distance of that object from the system, a presence detector mayneed to be calibrated. A presence detector can use one or moreultrasonic sensors to determine whether an object (such as a user) ispresent within a predetermined vicinity (e.g., detection field 530 ofFIG. 5A) of the system. During calibration, the presence detector cancreate a “static” environment model of that predetermined vicinity bydetermining what objects exist in that space. Thus, the staticenvironmental model represents what the presence detector “sees” when noobject is attempting a gesture. This can enable the presence detector tocompare “real-time” sensor data to the static model in order todetermine whether a “new” object is present. In addition, the staticmodel can further enable the presence detector to detect “new” objectseven if they are not moving within the predetermined vicinity.

Starting with the right hand side of the FIG., when the system begins aself-test or sensor calibration process (at step 1110), state machine1100 can transition to calibration paused state 1112. State 1112 canrepresent a condition in which calibration has not yet begun or in whichcalibration has been postponed because there has been recent movement asdetected by movement detector 1114. Movement detector 1114 can use a PIRsensor, for example, and is discussed in more detail below. If movementdetector 1114 detects movement, the state machine can revert tocalibration paused state 1112. If no movement is detected, the statemachine can proceed to calibrating state 1116. In state 1116, one ormore ultrasonic sensors can generate the static environmental model.When calibration is complete (at step 1118), the state machine canproceed to OFF state 1102.

An embodiment for creating a static environment model is now discussed.An alternative embodiment for creating a static environment model isalso discussed below in connection with FIGS. 18-21. The model can bedefined by a matrix of distances detected in the detection field of eachultrasonic sensor (e.g., ultrasonic sensors 320 of FIG. 3). The matrixdiscretizes the detected distances into separate buckets that arepopulated with counts, and it is the counts of these buckets that definethe static environment model. The matrix can be an n×m matrix defined byR_(ij) ^(s), where S is a particular ultrasonic sensor, i is the indexof a distance bucket (db_(i)), and j is the index of the sample. A totalof m samples may be taken, m is an integer. For example, in oneembodiment, m can be 100. A sampling size of one hundred can be achievedby calibrating each ultrasonic sensor for 10 seconds at a 10 hertzsampling rate. As discussed above, multiple ultrasonic sensors can existin the system. Referring to system 400, for example, ultrasonic sensor,S, can be sensor 420 or 422. Each distance bucket (db_(i)) represents aparticular distance that can be detected by the ultrasonic sensor. Thedistance buckets can range in distance from a minimum distance to amaximum distance, and each bucket can be separated by a predeterminedresolution. For example, in one embodiment, the minimum distance can beabout 660 mm and the maximum distance bucket can be about 3333 mm, andthe resolution can be about 60 mm. Thus, according to this exemplaryembodiment, the first distance bucket (db₁) can exist at 660 mm, thesecond (db₂) can exist at 720 mm, the third (db₃) can exist at 780 mm,and so on such that the last distance bucket exists at 3333 mm.

R_(ij) ^(s) is the number of distances that are within a predefinedproximity of distance bucket (db_(i)) observed on iteration j byultrasonic sensor, S. In one embodiment, an observed distance (d) canexist within a particular distance bucket if (db_(i))−30<d<(db_(i))+30.The +/−30 values can define the boundaries of the predefined proximityfor each distance bucket. For example, assume i is 5 and j is 12 and db₅is 1000 mm, and further assume that ultrasonic sensor. S, detecteddistances (d) at 990 mm and 1013 mm at sample iteration 12. As a result,R_(5,12) ^(s) is 2.

Each ultrasonic sensor is calibrated and is assigned its own R model.For example, referencing system 400, an R model is calibrated forultrasonic sensors 420 and 422. Once the R models are obtained for theultrasonic sensors, two additional arrays can be defined: r^(S) andq^(S). r^(S) is an array containing the means for each distance bucket.Thus, r_(i) ^(S)=sum_(j=1, . . . , m)(R_(ij) ^(S))/m. Relatively largevalues found in this array can represent the presence of an object.q^(S) is an array containing the variances for each distance bucket.Thus q_(i) ^(S)=var_(j=1, . . . , m)(R_(ij) ^(S)). Relatively largevalues found in this array can indicate objects are intermittently seenor are difficult to detect. The edge of a desk, a ceiling fan, or apiece of acoustically-absorbent material are examples of objects thatmay yield a relatively large variance. Knowledge of which distances arenoisy can better enable a presence detector to avoid false detection ofa “new” object.

FIG. 12 shows illustrative diagrams 1200 and 1210 that may form thecalibration basis of two different ultrasonic sensors according to anexample scenario. In particular, diagram 1200 can include r^(S) waveform1201, which may correspond to the mean values associated with a firstultrasonic sensor (e.g., sensor 420). Diagram 1210 can include r^(S)waveform 1211 may correspond to the mean values associate with a secondultrasonic sensor (e.g., sensor 422). The x-axis shows distance (infeet) and the y-axis represents the mean values. The spikes, which arelabeled as 1202-1205 in diagram 1200 and as 1212-1214 in diagram 1210,can represent detected objects. For example, in diagram 1200, objectsare detected at distances of approximately 3.9 feet, 5.4 feet, 7.8 feet,and 9.4 feet.

Referring now back to FIG. 11, and with particular reference to the lefthand side of the FIG., when the system enters into a state (step 1120)that may elicit motion or some other gesture action by a user, statemachine 1100 may transition to NO activity state 1122, as shown. Forexample, in the context of a hazard detection system, when such a systemis in an alarm mode or a pre-alarm mode, the system may expect tomonitor a user-based motion to silence the alarm or a pre-alarm message,and thus monitoring of motion may now be necessary. NO activity state1122 can represent a state in which no movement has been detected and nouser is currently present. In addition, when state machine 1100 is instate 1122, the ultrasonic sensors are not used and can be powered off.

If movement detector 1124 (e.g., a detector that uses PIR sensor data)does not detect any movement, state machine 1100 may remain in NOactivity state 1122. Movement detector 1124 can leverage the PIR sensordata segmentation process to compare the amplitude (e.g., y_(amplitude))of each detected motion event to a threshold. If the amplitude meets orexceeds the threshold, movement detector 1124 may conclude that someobject has moved within the field of view of the PIR sensor. In someembodiments, movement detector 1124 is the same as movement detector1114. If movement detector 1124 does detect motion, state machine 1100may transition to motion detected state 1126. Motion detected state 1126can represent a state in which a radiation sensing sensor such as a PIRsensor or an optical sensor has detected motion of at least one object,but there has not yet been any confirmation that that object is presentwithin a predefined vicinity of the system.

Presence detector 1128 may verify whether an object is present within avicinity of the system. Presence detector 1128 may construct a “dynamic”model based on real-time ultrasonic sensor data and compare to thestatic model in order to determine whether a “new” object is present. Ifno presence is detected, the state machine may revert back to motiondetector 1124. If presence is detected, the state machine may proceed toObject present state 1130. Object present state 1130 can represent thatan object is present within a predefined vicinity of the system. Whenthe system is in object present state 1130, it may provide an audiblemessage and/or visual cue to inform the occupant that he or she iscurrently being detected as present and that the system is ready toreceive a gesture input from the occupant. Presentation of the audiblemessage and/or visual cue can assist the occupant in positioning him orherself within an appropriate field of view of the hazard detectionsystem so that the system is better able to discern whether the occupantis implementing a gesture.

An embodiment for creating a dynamic environment model is now discussed,however, an alternative embodiment is discussed below in connection withFIGS. 18-21. The dynamic environment model may embody many of the sameelements as that used by the calibration engine to create the staticenvironment model. This model can be defined by a matrix of distancesdetected in the detection field of each ultrasonic sensor (e.g.,ultrasonic sensors 320 of FIG. 3). The matrix discretizes the detecteddistances into separate buckets that are populated with counts, and itis the counts of these buckets that define the dynamic environmentmodel. The matrix can be an n×m matrix defined by D_(ij) ^(s), where Sis a particular ultrasonic sensor, i is the index of a distance bucket(db_(i)), and j is the index of the sample. A total of m samples may betaken, and m is an integer. For example, in one embodiment, in can be20. A sampling size of twenty can net a two (2) second sampling windowat a 10 hertz sampling rate. A D matrix is maintained for each one ofthe multiple ultrasonic sensors that exist in the system. Each D matrixis updated with new sensor data and old data can be discarded. Thedistance buckets (db_(i)) used in the D matrices can be the same as thedistance buckets used in the R matrices (discussed above).

D_(ij) ^(s) is the number of distances that are within a predefinedproximity of distance bucket (db_(i)) observed on iteration j byultrasonic sensor, S. The predefined proximity can be bounded by thesame constraints as the R matrices. In one embodiment, an observeddistance (d) can exist within a particular distance bucket if(db_(i))−30<d<(db_(i))+30. The mean of real-time observed distances canbe defined by d_(i) ^(S)=sum_(j=1, . . . m)(D_(ij) ^(S))/m. Using d_(i)^(S) in combination with calibration arrays r_(i) ^(S) and q_(i) ^(S),presence detector 1128 can determine confidence values (c_(i) ^(S)) foreach distance bucket. In particular, the confidence values (c_(i) ^(S))can be defined as c_(i) ^(S)=(r_(i) ^(S)−d_(i) ^(S))²/q_(i) ^(S) fori=1, 2, . . . , n. The confidence value can represent confidence that adetected distance has exceeded the expected variance for a particulardistance bucket. If c_(i) ^(S) exceeds a predetermined “new object”variance threshold then presence detector 1128 can conclude that a newobject is present at the distance location of distance bucket (db_(i))of ultrasonic sensor, S. This distance can be referred to herein as thepresence distance. The predetermined variance threshold can be tuned toobtained a desired specificity/sensitivity balance for presence detector1128. For example, increasing the threshold can decrease sensitivity andincrease specificity, and decreasing the threshold can increasesensitivity and decrease specificity.

The presence distance of the new object can initially be defined asu=(u_(max)+u_(min))/2, where u is the average distance of the newobject, u_(max) is the maximum distance of the new object, and u_(min)is the minimum distance of the new object. If desired, a smoothingfunction may be used to update the value of u in order minimize thepotential for noise to disturb the accuracy of the new object'sdistance. For example, after an initial distance value of the new objectis obtained, the following smoothing function can be used:u=(a)(db_(i))+(1−a)u, where a can be within the range of 0.05 to 0.1.

FIG. 13 shows illustrative waveform diagrams 1300 and 1310 according toan example scenario. Both diagrams 1300 and 1310 include calibrationwaveforms and real-time data waveforms for two different ultrasonicsensors. In particular, diagram 1300 includes r^(S) waveform 1201 (thesame waveform as shown in FIG. 12) and real-time data waveform 1301associated with a first ultrasonic sensor. Real-time data waveform 1301can be the mean of the real-time observed distances, such as d_(i) ^(S)described above. When comparing waveform 1201 to waveform 1301, there isrelatively little variation between the two waveforms. This suggeststhat the ultrasonic sensor associated with waveforms 1201 and 1301 isnot detecting a new object. Diagram 1310 includes r^(S) waveform 1211(the same waveform as shown in FIG. 12) and real-time data waveform 1311associated with a second ultrasonic sensor. A comparison betweenwaveforms 1211 and 1311 indicates that a new object may exist atpresence distance 1320, which is shown to have a distance of 9.3 feet.

Referring back to FIG. 11, and state machine 1100 is in object presentstate 1130, gesture detector 1132 can determine whether a user isperforming a gesture. That is, gesture detector 1132 can be utilizedwhen state machine 1100 has progressed from motion detected state 1126to object present state 1130. Gesture detector 1132 can evaluate dataprocessed by motion detector 1124 and/or presence detector 1128 whenmaking a determination whether the user is performing a gesture. In oneembodiment, gesture detector 1132 may apply a set of criteria to apredetermined number of recently received motion detection events. Forexample, the predetermined number of can be the last two, three, or fourreceived motion events. Thus, if the predetermined number is three, thenall three motion events must satisfy the criteria in order for gesturedetector 1132 to recognize those three motion events as a user generatedgesture. The predetermined number of can be selected based on desiredsensitivity and specificity parameters of gesture detector 1132. Forexample, as the predetermined number increases, this can decreasesensitivity and increase specificity. Conversely, as the predeterminednumber decreases, this can increase sensitivity and decreasespecificity.

Some of the criteria may be applied to each motion event individuallyand some criteria may be applied to the combination of the motionevents. The criteria can include a motion event duration time limit.Thus, if the period of a motion event (e.g., t_(period)) exceeds themotion event duration time limit, then that motion event may bedisqualified as being a gesture. As an alternative to the time limit,the criteria may specify a range of periods that each motion event'speriod must fall within. The criteria can specify a range of amplitudeswithin which the motion event's amplitude (e.g., y_(amplitude)) must bein order to quality as a gesture event. The range of amplitudes may varybased on the presence distance, u, defined above. The criteria can applya standard deviation threshold to the amplitudes of each motion event.Thus, in order for the motion events to qualify, the amplitude of eachmotion event must be within a predetermined number of standarddeviations of an average amplitude of the combined motion events. Thecriteria can also apply variance thresholds to the motion events. Thus,in order for the combined motion events to qualify, the variance ofperiods must be less than a predetermined variance threshold. In someembodiments, gesture detector 1132 can recognize multiple differentgestures.

If gesture detector 1132 does not recognize a gesture, the state machinecan revert back to presence detector 1128. If a gesture is recognized,the state machine may proceed to gesture recognized state 1134. Oncestate machine 1100 reaches state 1134, the system may take appropriateaction responsive to the confirmation that a gesture is recognized. Forexample, in the hazard detection system context, a recognized gesturemay result in silencing of a loud sounding alarm or result in ceasingplayback of a pre-alarm message. The state machine may proceed to OFFstate 1102 after it reaches state 1134, as shown.

Various parameters within presence detector 1128 can be tuned toobtained a desired specificity/sensitivity balance. The distanceresolution can be a tunable parameter that can alter the sensitivity andspecificity of presence detector 1128 and the calibration thereof. Asmentioned above, the distance resolution defines the distance buckets.An increase in resolution can increase specificity and can decreasesensitivity. For example, by increasing the resolution, a new object canbe detected at more precise distances and thus may be less likely to beobstructed by objects in the ambient environment, but the new object maybe falsely detected due to a relatively low number of samples in eachdistance bucket. Conversely, a decrease in resolution can decreasespecificity and can increase sensitivity. For example, by decreasing theresolution, the sample size can be increased to provide more robuststatistics that enhances the confidence factor of whether a new objectis present, but objects in the ambient environment may tend tointerfere.

The variance threshold for qualifying new objects as being present canbe tuned to obtain a desired sensitivity/specificity balance. Asdiscussed above, the variance threshold is the threshold compared to theconfidence value at different distances. The variance threshold can be atunable parameter that can alter the sensitivity and specificityparameters of presence detector 1128.

FIGS. 14A-14C show an illustrative process for operating a hazarddetection system with gesture hush capability in accordance with anembodiment. This process can be implemented, for example, in a hazarddetection system that includes at least one hazard sensor, alarmgeneration circuitry, PIR sensor, and at least one ultrasonic sensor.For example, the hazard detection system can be system 200, 300, 400, or500 as discussed above. Starting with step 1002, data is received fromat least one hazard detection sensor. For example, the data can beobtained from one or more of sensors (e.g., ALS sensor 322, temperatureand humidity sensor 323, smoke detector 324, CO sensor 325, andthermistors 326). The sensor data can be analyzed to determine whether apre-alarm event or alarm event exists in the vicinity of the hazardsystem. A Pre-alarm event can be characterized as having similar sensordata as an alarm event, but does not have the same magnitude as thatwhich would cause an alarm event. In other words, pre-alarm event mayexhibit data qualities that surpasses a first threshold (which issufficient to trigger a pre-alarm event) but is less than a secondthreshold (which is sufficient to trigger an alarm event). An alarmevent may exhibit data qualities that equal or surpass the secondthreshold, and in some embodiments, may even surpass a third threshold,which is higher than the second threshold.

In some embodiments, the alarm event can be categorized as a hushablealarm event or a non-hushable alarm event. A hushable alarm event is onein which an audible alarm can be silenced (e.g., by pressing a button onthe hazard system or by performing a gesture hush in a vicinity of thesystem), and a non-hushable alarm event is one in which an audible alarmcannot be silenced. A hushable alarm event may exhibit data qualitiesthat equal or exceed the second threshold but are less than the thirdthreshold. A non-hushable alarm event may exhibit data qualities thatequal or exceed the third threshold. Different categorization of alarmevents may be needed to satisfy requirements of different jurisdictions.For example, in the United States, if the data qualities exceed thethird threshold, the audible alarm cannot be turned off.

After step 1402, the process proceeds to step 1410. At step 1410, adetermination is made whether the sensor data for the at least onehazard detection sensor exceeds a first threshold but not a secondthreshold. If the determination is NO, the process can proceed to step1415, which then reverts the process back to step 1402. If thedetermination is YES, the hazard detection system can enter into apre-alarm mode, and the process proceeds to step 1412 of FIG. 14B. Atstep 1412, a pre-alarm recording can be played back. The pre-alarmrecording can be any suitable message that can be played through aspeaker of the hazard detection system. The pre-alarm recording can bean informative message indicating that an alarm is imminent. Thepre-alarm may also instruct a user to perform a gesture event to preventthe hazard system from sounding its audible alarm in the event thesensor data is received that indicates the presence of an alarm event.At step 1413, sensor data acquired from at least one object detectionsensor is monitored. The monitored sensor data can include data obtainedfrom a PIR sensor, one or more ultrasonic sensors, or any otherradiation detecting sensor or image capturing sensor.

At step 1414, a determination is made as to whether the monitored dataindicates a gesture event has been performed. If the determination isNO, the process can proceed to step 1415, which then reverts the processback to step 1402. If the determination is YES, the process proceeds tostep 1416. At step 1416, playback of the pre-alarm recording can cease.In some embodiments, another recorded message can be played back inresponse to a detected gesture event. The other message can inform theuser, for example, that the gesture event has been recognized and thatthe audible alarm will be temporarily disabled. At step 1417, an audiblealarm is pre-emptively silenced in the event the sensor data for the atleast one hazard detection sensor exceeds a second threshold but not athird threshold. Thus, if the environmental conditions in and around thehazard detection system exhibit increased levels that would otherwisetrigger an alarm event, the monitored gesture event, which was receivedprior to the elevated levels, prevents an audible alarm from sounding.After step 1417, the process can proceed to step 1415, which returns theprocess back to step 1402.

Referring back to FIG. 14A, if the determination at step 1410 is NO, theprocess can proceed to step 1420. At step 1420, a determination is madewhether the sensor data for the at least one hazard detection sensorexceeds the second threshold but not a third threshold. If thedetermination is YES, the hazard detection system can enter into ahushable alarm mode, and the process can proceed to step 1422 of FIG.10C. At step 1422, an audible alarm is sounded. The audible alarm can,for example, be relatively loud and pulse at regular intervals. At step1423, sensor data acquired from at least one object detection sensor ismonitored. The monitored sensor data can include data obtained from aPIR sensor, one or more ultrasonic sensors, or any other motiondetecting sensor.

At step 1424, a determination is made as to whether the monitored dataindicates a gesture event has been performed. If the determination isNO, the process can proceed to step 1425, which then reverts the processback to step 1402. If the determination is YES, the process proceeds tostep 1426. At step 1426, the audible alarm can be silenced. In someembodiments, the audible alarm can be silenced for a predeterminedperiod of time, regardless of the hazard detection sensor readings. Inother embodiments, the audible alarm can be silenced for a predeterminedperiod of time, but can be sounded on demand based on hazard detectionsensor readings. After step 1426, the process can proceed to step 1425.

Referring back to FIG. 14A, if the determination at step 1420 is NO, theprocess can proceed to step 1430. At step 1430, a determination is madewhether the sensor data for the at least one hazard detection sensorexceeds the third threshold. If the determination is YES, the hazarddetection system can enter into a non-hushable alarm mode, and theprocess can proceed to step 1432. At step 1432, an audible alarm can besounded for an indefinite period of time or at least until the sensordata for the at least one hazard detection sensor drops below the thirdthreshold. If the determination is NO at step 1430, the process canproceed back to step 1402.

It is understood that the conditions for steps 1410, 1420, 1430 aremerely illustrative and that any suitable conditions can be used todetermine whether a pre-alarm event or alarm event exists. For example,various conditions for determining when pre-alarm and alarm events existcan be found be found in commonly assigned U.S. Pat. No. 9,412,258.

FIG. 15 shows an illustrative process in which a hazard detection systemsilences an audible alarm in response to monitoring a gesture inaccordance with an embodiment. Starting with step 1502, an audible alarmis emitted in response to a detected hazard event. For example, thedetected hazard event can be the presence of smoke in the vicinity ofthe hazard detection system. The audible alarm can be emitted by audiogeneration circuitry, such as alarm 334 of FIG. 3.

Then, at step 1504, a recording can be played back that providesinstructions on how to at least temporarily silence the audible alarm.For example, a pre-recorded message can be played through speaker 318 ofFIG. 3. In some embodiments, the recording can be played back if thehazard detection system detects motion. For example, if a motiondetection sensor, such as a PIR sensor, detects motion within its fieldof view, this may trigger playback of the recording. As another example,playback of the recording may be triggered if an ultrasonic sensordetects presence of an object within its field of view.

At step 1506, an object is detected moving in a vicinity of the hazarddetection system in accordance with the instructions of the recording.In this step, one or more object detecting sensors may detect the objectmoving within their respective fields of view. Moreover, data acquiredfrom these sensors can indicate that a gesture event was detected. Thegesture event may be any suitable movement or combination of movements.In one example, the gesture event can be a waving motion of one or twoarms.

At step 1508, the audible alarm is at least temporarily silenced inresponse to detecting the object moving in accordance with theinstructions of the recording. In this step, the audible alarm is turnedOFF in response to an affirmative command by a user. The audible alarmmay remain OFF for a predetermined period of time before beingreactivated, at which time the user may have to commence another gestureevent to silence it.

FIG. 16 show an illustrative process for operating a hazard detectionsystem equipped with at least one ultrasonic sensor in accordance withan embodiment. Starting at step 1602, alarm generation circuitry can beactivated to emit an audible alarm. The audible alarm can be activated,for example, in response to data received by one or more hazarddetection sensors. Next, at step 1604, at least one ultrasonic detectionfield can be monitored for presence of at least one object. For example,the ultrasonic detection field can be detection field 530 of FIG. 5A orFIG. 6D. At step 1606, a determination is made whether the at least oneobject is moving in accordance with a gesture while the at least oneobject is present in the at least one ultrasonic detection field. Forexample, the moving arms of person 600 in FIG. 6D can be an objectmoving in accordance with a gesture while within ultrasonic detectionfield 530.

At step 1608, the alarm generation circuitry is deactivated to ceaseemitting the audible alarm when it is determined that the at least oneobject is moving in accordance with the gesture while the at least oneobject is present in the at least one ultrasonic detection field. Themoving object and the object present within an ultrasonic field can bethe same or different. For example, referring briefly to FIG. 6D, thebody of person 600 may be present and stationary within detection field530, but the arms can be moving in and out of detection field 530. Thepresence of the body can be sufficient to satisfy the presencerequirement within an ultrasonic field, and the movement of the arms canbe sufficient to satisfy the gesture movement.

FIG. 17 show an illustrative process for operating a hazard detectionsystem equipped with a PIR sensor and at least one ultrasonic sensor inaccordance with an embodiment. Beginning with step 1702, an audiblealarm can be emitted in response to a hazard event detected by the atleast one hazard detection sensor. At step, 1704, sensor data can bereceived from a passive infrared (PIR) sensor. The PIR sensor has arelatively wide field of view for detecting movement of at least oneobject. At step 1706, sensor data is received from at least oneultrasonic sensor, each ultrasonic sensor having a relatively narrowfield of view for detecting presence of the at least one object. Thenarrow field of view is less than the wide field of view.

Then, at step 1708, data acquired by the PIR sensor and the at least oneultrasonic sensor can be processed. The data can be processed, forexample, by control circuitry (e.g., system processor 310). At step1710, a determination is made whether a gesture hush event exists in theprocessed data. For example, the control circuitry can analyze theamplitude and period of waveforms in the processed data. Examples ofthese waveforms are discussed above in connection with FIGS. 9A-9D.Then, at step 1712, the audible alarm ceases to sound when the gesturehush event is determined to exist.

Alternative embodiments for calibrating the ultrasonic sensors,detecting presence of new objects using the ultrasonic sensors, anddetecting a gesture are now discussed, with occasional reference to thestate machine of FIG. 11. Calibration of the ultrasonic sensors is nowdiscussed. In particular, the calibration process, which is shown on theright hand side of FIG. 11, can be implemented by generating a histogramof all distances sensed by each ultrasonic sensor. When generating thehistogram, a count is added to each distance bucket sensed by theultrasonic sensor. A distance bucket can exist between a pre-definedrange of distances, separated by a fixed interval. For example, therange can be between one foot and ten feet, with buckets separated by0.2 feet. Thus, a first distance bucket can exist between 1 foot and 1.2feet, the next can exist between 1.2 feet and 1.4 feet, and the next canexist between 1.4 feet and 1.6 feet, and so on until the last bucketreaches 10 feet. In addition, for each detected distance, a count isadded to both adjacent distance buckets. For example, if an object isdetected within distance bucket X, a count is added to distance bucketX, and a count is added to distance buckets X−1 and X+1. Adding countsto adjacent distance buckets can account for variances in ultrasonicsensor's ability to detect objects at different distances.

After the histogram of distance buckets for each ultrasonic sensor isobtained, a filter can be applied to it to generate a binary matrix foreach sensor. The binary matrix represents whether an object exists ateach distance bucket for the entire range of distances. An object may beconsidered to exist at a particular distance bucket if the number ofcounts in that bucket meet or exceed a threshold set by the filter.Thus, if the number of counts for a given bucket meets or exceeds thethreshold, a binary “1” may be stored in the binary matrix correspondingto that distance bucket. If the number of counts for a given bucket doesnot meet or exceed the threshold, that bucket is stored as a binary “0.”This filter threshold can help eliminate any noise that may be presentin the histogram. In some embodiments, the filter can ensure that thebinary 1s assigned to various distance buckets in the matrix areindicative of a higher likelihood than not, that an object is present atthose distances. An exemplary calibration matrix 1801 is shown in FIG.18, where C represents a binary calibration matrix for one of theultrasonic sensors. As shown, matrix 1801 has n different distancebuckets, as indicated by db₁, db₂, db₃ and so on until db_(n). Eachposition in matrix 1801 corresponds to a different distance bucket. A“1” indicates an object is present at that distance bucket, and a “0”indicates no object is present at that distance bucket. A calibrationmatrix can be obtained for each ultrasonic sensor at regular intervals(e.g., once a day).

During non-calibration usage of the ultrasonic sensor, such as duringexecution of the lefthand side of the flowchart of FIG. 11, andparticularly for presence detection step 1128, a real-time binary sensormatrix can be generated for each ultrasonic sensor. The same criteriaused for generating the calibration matrix may be used for generating asensor matrix. An exemplary real-time sensor matrix 1811 is shown inFIG. 18, where S represents a real-time binary sensor matrix for one ofthe ultrasonic sensors. As shown, matrix 1811 includes the same numberof distance buckets as matrix 1801 and each position in matrix 1811 ispopulated with either a “1” or “0” depending on whether an object isdetected as present.

A comparison between matrix 1801 and matrix 1811 indicates whether anynew objects have been added or any old objects have been lost. An objectis added if the real-time sensor matrix indicates the presence of anobject at a particular distance bucket that did not exist in thecalibration matrix. For example, in comparing db2 of both matrices, anew object is added because a “1” now exists in matrix 1811, whereas incalibration matrix 1801, no object previously existed at that distancebucket. An object is lost if it exists as a present object in thecalibration matrix, but is no longer detected as present in thereal-time sensor matrix. Comparing db7 of both matrices, an old objectis lost because matrix 1801 previously detected the presence of anobject, but according to matrix 1811, that object is no longer present.For example, whereas during calibration the sensor may have detected awall at db7, but during usage, the presence of a user may prevent thesensor from seeing that wall.

The result of the comparison between matrices 1801 and 1811 can indicatewhether an object is present. Any suitable formula or criteria can beused to determine whether an object is present within an ultrasonicsensor's field of view. For example, in one embodiment, an object can beconsidered present if the number of newly added objects is equal to orgreater than a first predetermined number (e.g., two), or if the numberof newly added objects is equal to or greater than a secondpredetermined number (e.g., one) and the number of lost objects is equalto or greater than a third predetermined number (e.g., one). Referringbriefly to FIG. 11, if the comparison between matrices 1801 and 1811indicates that an object is present at step 1128, then the state machineof FIG. 11 can transition to object present state 1130.

In some embodiments, different criteria can be used for one or more ofthe ultrasonic sensors. For example, if the hazard detection device ismounted on the ceiling, a first set of criteria may be used. However, ifthe hazard detection device is mounted to a wall, a second set ofcriteria may be used. A ceiling mounted device may require lessstringent criteria than a wall mounted device. These different criteriacan be used in different stages of the state machine of FIG. 11. In someembodiments, the device can determine how it is mounted based onaccelerometer data, if it is equipped with an accelerometer. If there noaccelerometer or other device that indicates device orientation, thedevice can infer how it is mounted based on data obtained from itsultrasonic sensors. For example, if the angled ultrasonic sensor (e.g.,sensor 423) is detecting a relatively large percentage of presentobjects (e.g., more than 60%, more than 70%, or more than 80%), then itcan be inferred that the device is mounted to the wall. If both thestraight and angled sensors (e.g., sensors 421 and 423) are detectingobjects in approximate equal percentages, then it can be inferred thatthe device is mounted to the ceiling.

After an object is detected as present, gesture detector 1132 may needto know which ultrasonic sensor is detecting the presence of the object.This determination can be made dynamically by calculating which sensorhas the largest number of distance changes. The number of distancechanges can be calculated by adding the number of newly added objects tothe number of objects lost. For example, referring to matrices 1801 and1811 of FIG. 18, the number of distance changes for that particularultrasonic sensor is 2, since there is one added object and one lostobject. If, for example, the number of distance changes for the otherultrasonic sensor (not shown) is one, then the ultrasonic sensorassociated with matrices 1801 and 1811 may be deemed as the actualsensor sensing presence of the object. When a sensor is chosen as the“correct” sensor, the state machine may stick with this sensor fordetermining whether a gesture is detected at step 1132 until it nolonger sees the object.

Moreover, as part of gesture detection at step 1132, the state machinemay use a distance settling algorithm to reduce potential for falsepositives. The distance settling algorithm may be able to determineperiods of time when an occupant is detected within a field of view ofan ultrasonic sensor, and is not moving closer to or away from thehazard detection device. For example, the distance settling algorithmcan discern when an occupant enters a room containing the hazarddetection system, when the user stops moving towards or away from thehazard detection system, and when the user exits the room. In order tominimize or prevent false positives, it may be desirable to ignore PIRgesture motions unless the occupant is relatively still. Thus, if theoccupant is moving (e.g., walking into or out of the room), then any PIRgesture motions may be ignored. However, if the user is relatively stilland is moving his or her arms and hands to implement a gesture motion,this motion may be processed as a potential gesture motion.

Referring now to FIG. 19A, an illustrative waveform 1901 is shown.Waveform 1901 can represent distances detected by one of the ultrasonicsensors over time. In one embodiment, waveform 1901 may be based on dataobtained from the ultrasonic sensor determined to be detecting presenceof the object. Waveform 1901 can be generated by ascertaining theclosest distance added during each sample period. As shown, at time, t1,a new distance is added at a relatively far distance away from thesensor (shown as d1), but as time progresses, the new distances addedappear as decreasing distances to the sensor, until it the distancessettle out around d2. An occupant may have walked into a room betweentimes t1 and t2 and stopped moving towards or away from the sensorbetween times t2 and t3. The user, however, may be moving his or herarms or hands between times t2 and t3. After time t3, the occupant mayhave walked out of the room because the new added distances increase indistance away from the sensor.

The distance settling algorithm may generate a derivative waveform 1911,as shown in FIG. 19B, based on the closest distance sampling describedabove in connection with FIG. 19A. Derivative waveform 1911 may berepresented by an absolute value of the differences of waveform 1901. Asshown, the peaks of waveform 1911 correspond to the relatively largedistance changes between times t1 and t2, and between times t3 and t4.In addition, the flat portion of waveform 1911 corresponds to therelatively unchanging portion of waveform 1901. The distance settlingalgorithm can impose threshold 1913 on waveform 1911 to determine whenthe occupant is settled or not. If any portion of waveform 1911 exceedsthreshold 1913, then it can be considered that the occupant is notsettled and no gesture processing inputs will be processed whilewaveform 1911 is considered not settled. Thus, as shown, since waveform1911 exceeds threshold 1913 between times t1 and t2, and again betweentimes t3 and t4, no gesture inputs may be considered within thesetimeframes. Thus, even if the PIR sensor is detecting a waving motionbetween either times t1 and t2 or times t3 and t4, these PIR sensorreadings may be discarded. However, if the PIR sensor is detectingmotion between times t2 and t3, for example, the PIR sensor dataobtained during this time period may be used by a gesture detectionalgorithm.

The gesture detection algorithm (such as the algorithm processed at step1132 of FIG. 11) can analyze PIR sensor data during settled periods, asdetermined by the distance settling algorithm, to determine whether agesture motion (e.g., a wave) exists in the PIR sensor data. The PIRsensor data may be analyzed by first determining the peaks in the PIRsensor data. Peaks can be ascertained using, for example, a slope changedetection method or a zero-cross detection method. In the slope changedetection method, changes from positive to negative slope can mark a maxof a peak, and changes from negative to positive can mark a minimum of apeak. If desired, hysteresis can be built into the slope change detectorto ignore sudden and abrupt slope changes. This can be accomplished byapplying thresholds to qualify peaks as a max peak or a minimum peak.For example, in order for a peak to be considered a max peak, thewaveform must drop a predetermined number below the max peak. If itdoes, then the peak can be recognized as a max peak. This can guardagainst a situation where a peak is reached, then the waveform drops aminiscule amount and the starts rising again to another peak. But forthe threshold, this miniscule peak would be registered as a peak. Thesame basic principle applies to minimum peaks. When a minimum peak isreached, the waveform must rise at least a predetermined amount Once themax and min peaks are found, the amplitude and period of the gesturescan be ascertained. In the zero-cross method an average value of the PIRsensor data is obtained, and compared to the raw PIR sensor data. Zerocrosses occur when the average value of PIR sensor data intersects withthe raw PIR sensor data. The amplitude and period of the PIR sensor datacan be obtained from the zero crosses. In some applications, the slopechange detector may more applicable, whereas in other applications, thezero-cross detector may be more applicable. For example, since wave-likegesture motions are fairly consistent—thereby producing a relativelynon-noisy signal—the slope change detector may be the more suitabledetector for detecting waves. However, when the PIR data is relativelynoisy, the zero cross detector may be the more suitable detector fordetecting motions in the PIR data.

Regardless of which detector is used, the amplitude and period of eachgesture motion is obtained. For example, FIG. 20 shows an illustrativegesture waveform 2001, which may represent a wave gesture. Waveform 2001has amplitude A1 and period P1. If the amplitude and period of thewaveform meet predefined criteria, then the amplitude and period of thatwaveform are stored in a rolling buffer of wave gestures. The predefinedcriteria can define the lower and upper bounds for the amplitude and thelower and upper bounds of the period. FIG. 21 shows illustrative buffer2101. The rolling buffer of wave gestures can store a fixed number ofwaves. For example, as shown in buffer 2101, four waves are stored. Aseach new wave satisfying the predefined criteria is obtained, it isrolled into the buffer. If the buffer is full, the new wave can push outan old wave. This way, the buffer stores the newest waves satisfying thecriteria. If no new waves satisfying the predefined criteria arereceived within a predetermined period of time, the buffer is cleared.

When buffer 2101 has stored therein two or more waves, pair wisecombinations of waves are compared to determine whether a comparisonbetween two waves satisfies a set of conditions. As shown in FIG. 21,three different pair wise combinations are shown, Pw1, Pw2, and Pw3. Pw1can be a comparison between wave 1, which includes A1 and P1, and wave2, which includes A2 and P2. Pw2 can a comparison between wave 2, whichincludes A2 and P2, and wave 3, which includes A3 and P3. Pw3 can acomparison between wave 3, which includes A3 and P3, and wave 4, whichincludes A4 and P4. If desired, a pairwise combination can be madebetween wave 1 and wave 3, or between wave 2 and wave 4.

For each pair wise comparison, the average amplitude and average periodof two waves may be applied to a set of conditions. The conditions canspecify upper and lower bounds of the average amplitude and upper andlower bounds of the average period. If the average amplitude and averageperiod of the pair wise combination meet the conditions, the two wavesmay be considered to be a matched wave pair. In some embodiments, onematched wave pair may be sufficient to qualify as a detected wavegesture. In other embodiments, two or more matched wave pairs may berequired in order for the PIR sensor data to qualify as a detected wavegesture. It is understood that the pair wise comparison can be made withsettled and unsettled PIR data, and that the gesture detection algorithmaccording to various embodiments can decide how best to use the settledand unsettled factors in evaluating the PIR data.

Referring now to FIGS. 22-25, a shape matching algorithm for detectingwave events in a PIR sensor waveform is discussed. The shape matchingalgorithm may be implemented at the gesture detection step 1132 of FIG.11, and as its name implies, it searches for repetitive pattern shapesacross successive periods to determine whether the PIR sensor iscapturing a wave event. The shape matching algorithm can do this byslicing the PIR waveform into several windows, analyzing the waveformpattern in each window, and determining whether periodic matchingpatterns occur within that window. If a sufficient number of matchingpatterns are detected, then it may be inferred that a wave event isdetected. The algorithm calculates a difference between a scaled“non-wave” score and a “wave” score and compares that difference to athreshold. If the difference exceeds the threshold, a “wave” pattern isdetected. The shape matching algorithm can be expressed by the followingequation:α×c1−c2>t   (1)where α is a weighting factor used to scale C1, C1 is the score of anon-wave within a window of samples, W (not shown), C2 is the score of awave within the same window of samples, W, and t is the threshold fordetermining whether a pattern match is detected. The window, W, includesa fixed number of samples that are used to compute C1 and C2. The sizeof the window can be changed to adjust the number of samples used tocompute C1 and C2. The values selected for α and t and may depend on thesize of W. For example, a larger sized W may result in a higher t,whereas a smaller sized W may result in a lower t.

The formula in equation 1 may represent a simplified statisticalexpression of whether a wave pattern is detected. The C1 and C2 termsmay each represent a score based on a negative log of a probabilityfunction, where the probability function of C1 is mathematically relatedto a non-wave probability (illustratively shown by equation 2) and theprobability function of C2 is mathematically related to a waveprobability (illustratively shown by equation 3). The probabilityfunctions of equations 2 and 3 may each resemble a likelihood function.Thus equation 2 may describe the probability a particular sequence ofsamples is observed given that the source of samples is not a wave, andequation 3 may describe the probability a particular sequence of samplesis observed given that the source of samples is a wave.

$\begin{matrix}{{P\left( {{samples}❘{{is\_ not}{\_ wave}}} \right)} = {\prod\limits_{i \in W}\;{\frac{1}{c_{1}}e^{- \frac{{({x_{i} - {({x_{i - 1} + {\Delta\; x_{i - 1}}})}})}x^{2}}{2\;\sigma_{1}^{2}}}}}} & (2) \\{{P\left( {{samples}❘{is\_ wave}} \right)} = {\prod\limits_{i \in W}\;{\frac{1}{c_{2}}e^{- \frac{{({x_{i} - {({x_{i - 1} + {\Delta\; x_{i - \lambda}}})}})}x^{2}}{2\;\sigma_{2}^{2}}}}}} & (3)\end{matrix}$

Equations 2 and 3 can by simplified by taking the negative logarithm ofeach probability function, thereby eliminating the exponential terms. Asresult, C1 and C2 may also be mathematically related to a negative loglikelihood function. However, the C1 and C2 used in equation 1 may notbe strictly represented by either the probability function or thenegative log likelihood function because equation 1 uses the weightingfactor, α, and the threshold, t, to “absorb” and simplify all otherconstant terms (e.g., σ₁ and σ₂) from which equation 1 is derived. Thevalues selected for α and t may be chosen to optimize the performance ofthe shape matching algorithm.

The non-wave score, C1, and wave score, C2, are both calculated usingthe same window of samples, W. The non-wave score, C1, represents aprobability that the samples within the sample size, W, are not part ofa wave. This calculation is the sum of the square of the differentialbetween successive samples within the sample size. This calculation canbe expressed by the following equation:Σ_(iϵW)(Δx _(i) −Δx _(i−1))²  (4)where W is the sample size, Δx_(i) is the difference between the currentsample, xi, and the previous sample, x_(i−1), and Δx_(i−1) is thedifference between the previous sample, x_(i−1) and two samples prior,x_(i−2). In other words, each score calculation represents whether thecurrent sample “appeared” where it was expected to be. A relatively lownon-wave score (C1) may be interpreted that, under an assumption for thegiven set of samples, that the user is not waving. FIG. 22 illustrates atiming diagram of a PIR waveform 2202. As shown, x_(i) is expected to bethe location shown, based on the location of prior samples in waveform2202. If the samples appear to be occurring where they are expected tobe (e.g., shown as the expected location for x_(i)), then theprobability that the PIR samples represent a non-wave may be relativelyLOW and as a result, the calculated score may be relatively HIGH. If thesamples do not appear to be occurring where they expect to be (e.g.,they are randomly jumping all over the place, which is shown in the FIG.as the not expected location for x_(i)), then the probability that thePIR samples represent a non-wave are relatively HIGH, and as a result,the calculated score may be relatively LOW.

The wave score, C2, represents a probability that the samples within thesample size, W, are part of a wave. This calculation is the sum of thesquare of the differential between a current sample and (the currentsample one lambda ago, where lambda is a period of a wave). In otherwords, each wave score calculation represents whether a wave exists at aperiodic interval, where the period is represented by lambda, λ. Thecalculation can be expressed by the following equation:Σ_(iϵW)(Δx _(i) −Δx _(i−λ))²  (5)where W is the sample size, Δx_(i) is the difference between the currentsample, xi, and the previous sample, x_(i−1), and Δx_(i−λ)is thedifference between the sample one lambda ago, x_(i−λ), and the priorsample one lambda ago, x_(i−λ−1). A relatively low wave score (C2) maybe interpreted that, under an assumption for the given set of samples,that the user is waving. FIG. 23 shows an illustrative waveform of PIRwaveform 2302. FIG. 23 also shows the λ, Δx_(i−Δ), x_(i), Δx_(i−1),ΔX_(i) Thus, using equation 5 above, the result calculates the score ofwhether Δx_(i) resembles Δx_(i−λ) k for period, λ. As illustrated inwaveform 2302, Δx_(i) closely resembles Δx_(i−λ). As such theprobability that a wave exists for period, Δ, is HIGH, and the resultingvalue of the wave probability calculation for x_(i) is LOW. However, ifΔx_(i) does not closely resemble Δx_(i−λ), then the probability that awave exists is LOW, and the resulting value of the wave scorecalculation is HIGH.

Equation 1 specifies that it is the balance between C1 and C2 (alongwith α and t) that determines whether a wave pattern is detected. Thatis, the shape matching algorithm compares C1 and C2 to each other anddoes not evaluate each of C1 and C2 independently to determine whether apattern is detected. For example, assume a sequence of samples were allthe same (a flatlined sensor). In such a sequence, the C2 wave scorewould be zero, and since lower values mean higher likelihood, this couldbe interpreted to indicate that the probability of wave was high.However, as equation 1 specifies, it is the balance between the C1 andC2 terms (and α and t) that dictates whether a wave pattern is detected,because the C1 non-wave score would also be zero for the same sequence.Thus, irrespective of α, the non-wave score may have to higher than thewave score in order for the shape matching algorithm to detect a wavepattern.

The shape matching algorithm may calculate a wave score, C2, for severaldifferent waving periods. For example, the shape matching algorithm maycalculate C2 for waving periods ranging between λ_(min) and λ_(max). Forexample, FIG. 24 shows an illustrative PIR waveform 2402 sampling withinwindow W, and several different waving periods. Any suitable number ofwaving periods may be used to calculate a corresponding number of wavescores, C2. As shown, FIG. 24 has waving periods, λ_(min), λ_(min+1),λ_(min+2), and λ_(max), each of which start at position (i). The shapematching algorithm may calculate a wave score for each of the multiplewaving periods to find a best fit match with a user's actual wave. Afterthe wave scores for all waving periods are calculated, the shapematching algorithm may select the smallest calculated score for use inequation 1, as the smallest calculated number represents the best match.

In practice, the user's actual wave may not have a constant period. Thatis, when the user is waving, the movements may have the same approximatewave motion, but each wave is not exactly the same. The shape matchingalgorithm can take these variations into account by incorporatingtolerance factors for each λ period calculation. This way, the shapematching algorithm can detect period pattern matches even though theyare not exactly the same. For example, a C2 that takes the variationsinto account may be expressed by equation 6:Σ_(iϵW)min_(sϵ[−ΔλΔλ])(Δx _(i) −Δx _(i−λ+s))²  (6)where the variable s represents the “slack” that varies over the rangeof λ_(min) and λ_(max). After each C2 is calculated according toequation 6, the smallest calculated C2 is chosen for use in equation 1.

FIG. 25 shows an illustrative flowchart of steps that may be executed bya shape matching algorithm according to an embodiment. These steps maybe executed, for example, after it is determined a user is present byanalyzing ultrasonic data. As another example, these steps may beperformed in step 1132 of FIG. 11. Starting with step 2502, PIR signalsmay be received from a PIR sensor. For example, the PIR sensor may bePIR sensor 327 of FIG. 3. Then, at step 2504, a window of PIR samplescan be selected for wave event evaluation. The size of the window mayvary to include a desired sample set of PIR signals. In someembodiments, the size of each window used may be the same for eachsuccessive wave event evaluation. In other embodiments, the size of thewindows may vary from one wave event evaluation to the next. Forexample, a first window may include X samples, and a second window mayinclude Y samples, where Y is greater than X. A sequence of windows mayinclude any combination of windows (e.g., five instances of a firstwindow, followed by three instances of a second window, followed by fiveinstances of the first window, and so on).

Furthermore, in another embodiment, the windows for successive waveevent calculations may or may not overlap. For example, anon-overlapping wave event calculation may include an exclusive sampleset. That is, the samples used for each calculation are used only forthat calculation and no other samples. Overlapping wave events can usenon-exclusive sample sets. That is, the same sample may be used by morethan one wave event calculation. Computational overhead may increasewhen calculating wave events for overlapping windows.

At step 2506, a non-wave score for the sample set may be calculated. Asdiscussed above, the shape matching algorithm may use equation 4 tocalculate the non-wave score. A wave score may also be calculated forthe same sample set, at step 2508. As also discussed above, the shapematching algorithm may use equation 5 or 6 to calculate the wave score.At step 2510, the non-wave score may be scaled by a constant, α, whichmay have a value based on a number of factors, including, for example,the size of the window.

At step 2512, a determination may be made as to whether a differencebetween the scaled non-wave score and the wave score exceed a threshold,t. This determination can be represented by equation 1, as discussedabove. The threshold, t, may be based on any suitable number of factors,including the value of the scaling constant, α, and the size of thewindow. If the determination at step 2512 is YES, a wave detectioncounter may be increased, as indicated by step 2514. If thedetermination at step 2512 is NO, a miss counter may be incremented (asindicated at step 2515). At step 2516, a determination is made whetherthe miss counter exceeds a miss threshold. If the determination is YES,the wave detection counter may be reset (as indicated by step 2517), andthe process loops back to step 2502, where the shape matching algorithmevaluates wave detection for another sample set of data. If thedetermination at step 2516 is NO, the process may loop back to step2502. Continuing on to step 2518, a determination is made as to whetherthe wave detection counter exceeds a wave count threshold. If thedetermination is NO, the process loops back to step 2502. If thedetermination is YES, a wave may be detected, as indicated by step 2520.

It is to be understood that the steps shown in the flowcharts of one ormore of FIGS. 11, 14A-14C, 15-17, and 25 are merely illustrative andthat existing steps may be modified or omitted, additional steps may beadded, and the order of certain steps may be altered.

It is understood that although the embodiments described herein withrespect to a hazard detection system, these embodiments may also be usedin any system or device where it is desired to maintain sensing andmonitoring of other events while updating the operational capabilitiesof one of more components of that system or device. For example, theother events can include events that are not necessarily tied to hazardssuch as smoke, CO, and heat, but can include motion detection, sounddetection, and the like. Events reported by remote devices may also betaken into account. For example, security device such as window and doorsensor, and motion detection sensors that provide feedback to a systemmay quality as other events.

Moreover, the processes described with respect to FIGS. 1-25, as well asany other aspects of the invention, may each be implemented by software,but may also be implemented in hardware, firmware, or any combination ofsoftware, hardware, and firmware. They each may also be embodied asmachine- or computer-readable code recorded on a machine- orcomputer-readable medium. The computer-readable medium may be any datastorage device that can store data or instructions which can thereafterbe read by a computer system. Examples of the computer-readable mediummay include, but are not limited to, read-only memory, random-accessmemory, flash memory, CD-ROMs, DVDs, magnetic tape, and optical datastorage devices. The computer-readable medium can also be distributedover network-coupled computer systems so that the computer readable codeis stored and executed in a distributed fashion. For example, thecomputer-readable medium may be communicated from one electronicsubsystem or device to another electronic subsystem or device using anysuitable communications protocol. The computer-readable medium mayembody computer-readable code, instructions, data structures, programmodules, or other data in a modulated data signal, such as a carrierwave or other transport mechanism, and may include any informationdelivery media. A modulated data signal may be a signal that has one ormore of its characteristics set or changed in such a manner as to encodeinformation in the signal.

It is to be understood that any or each module discussed herein may beprovided as a software construct, firmware construct, one or morehardware components, or a combination thereof. For example, any one ormore of the modules may be described in the general context ofcomputer-executable instructions, such as program modules, that may beexecuted by one or more computers or other devices. Generally, a programmodule may include one or more routines, programs, objects, components,and/or data structures that may perform one or more particular tasks orthat may implement one or more particular abstract data types. It isalso to be understood that the number, configuration, functionality, andinterconnection of the modules or state machines are merelyillustrative, and that the number, configuration, functionality, andinterconnection of existing modules may be modified or omitted,additional modules may be added, and the interconnection of certainmodules may be altered.

Whereas many alterations and modifications of the present invention willno doubt become apparent to a person of ordinary skill in the art afterhaving read the foregoing description, it is to be understood that theparticular embodiments shown and described by way of illustration are inno way intended to be considered limiting. Therefore, reference to thedetails of the preferred embodiments is not intended to limit theirscope.

What is claimed is:
 1. A battery-operated smart-home device, comprising:power control circuitry for receiving electrical power from a batteryand providing electrical power to the smart-home device; a speaker; avisual indicator; an event sensing system for determining occurrence ofan event; an acoustic sensing system configured to sense, using acousticsignals, a presence of a person within a first field of view; aninfrared sensor; and a processing system controlling each of saidspeaker, said visual indicator, said event sensing system, said acousticsensing system, and said infrared sensor, wherein said processing systemis configured to: determine the occurrence of the event; and responsiveto the occurrence of the event: provide increased electrical power tosaid acoustic sensing system; increase a sampling rate of said infraredsensor; process acoustic signals received by said acoustic sensingsystem to determine the presence of the person within the first field ofview; output, using at least one of said speaker and said visualindicator, feedback to the person indicating that the person is in thefirst field of view and the smart-home device is ready to detect andprocess a gesture; process readings from at least said infrared sensorto determine that the person has made a particular gesture; and performan action corresponding to the particular gesture.
 2. The smart-homedevice of claim 1, further comprising an orientation sensor capable ofdetermining an orientation of the smart-home device relative to a room,wherein: the acoustic sensing system is operable to determine presencein each of the first field of view and a second field of view; andresponsive to a detected orientation of the smart-home device relativeto the room, said processing system disables one of said first andsecond fields of view of said acoustic sensing system.
 3. The smart-homedevice of claim 2, wherein the smart-home device is configured formounting on one of a wall and a ceiling, and the orientation sensorcomprises a multi-axis accelerometer.
 4. The smart-home device of claim1, wherein the acoustic sensing system comprises an ultrasonic sensor.5. The smart-home device of claim 1, wherein the event sensing systemcomprises a hazard sensing device, and wherein the event is a hazardevent that causes an alarm to sound, and wherein the particular gesturecorresponds to an alarm hush, and the action performed corresponding tothe particular gesture hushes the alarm.
 6. The smart-home device ofclaim 1, wherein signals from the infrared sensor are processed todetermine whether a periodic pattern exists that is indicative of aperiodic hand waving gesture.
 7. The smart-home device of claim 1,wherein the speaker is operative to emit voice instructions to theperson when the person is detected to be within the first field of view.8. A smart-home device, comprising: a speaker; a visual indicator; anevent sensing system for determining occurrence of an event; a firstsensor system operative to verify presence of a person within a firstfield of view; a second sensor system operative to detect gesturesperformed by the person when the person is in the first field of view;and a processing system controlling each of said speaker, said visualindicator, said event sensing system, and said first sensor system, andsaid second sensor system, wherein said processing system is configuredto: determine the occurrence of the event; and responsive to theoccurrence of the event: increase a sampling rate of said second sensorsystem; output, using at least one of said speaker and said visualindicator, feedback to the person when the first sensor system confirmsthat the person is in the first field of view and the smart-home deviceis ready to detect and process a gesture; process readings from at leastsaid second sensor system to determine that the person has made aspecific gesture; and perform an action corresponding to the specificgesture.
 9. The smart-home device of claim 8, wherein the second sensorsystem comprises a radiation-based sensor.
 10. The smart-home device ofclaim 8, wherein the first sensor system comprises a sensor that usestime-of-flight calculations to determine location of an object withinthe first field of view.
 11. The smart-home device of claim 8, whereinthe first sensor system comprises a radio frequency sensor.
 12. Thesmart-home device of claim 8, wherein the event sensing system comprisesa hazard sensing device, and wherein the event is a hazard event thatcauses an alarm to sound, and wherein the specific gesture correspondsto an alarm hush, and the action performed corresponding to the specificgesture hushes the alarm.
 13. The smart-home device of claim 8, whereinthe readings from the second sensor system are processed to determinewhether a periodic pattern exists that is indicative of a periodic handwaving gesture.
 14. The smart-home device of claim 8, wherein thespeaker emits voice instructions to the person when the person isdetected to be within the first field of view.
 15. The smart-home deviceof claim 8, wherein the visual indicator is operative to light up orrapidly blink when the person is detected to be within the first fieldof view.
 16. A method implemented in a battery-operated smart-homedevice, the smart-home device comprising power control circuitry forreceiving electrical power from a battery and providing electrical powerto the smart-home device; a speaker; a visual indicator; an eventsensing system for determining occurrence of an event; an acousticsensing system configured to sense, using acoustic signals, a presenceof a person within a first field of view; an radiation based sensor; anda processing system, the method comprising: determining the occurrenceof the event; and responsive to the occurrence of the event: providingincreased electrical power to said acoustic sensing system; increasing asampling rate of said radiation based sensor; processing acousticsignals received by said acoustic sensing system to determine thepresence of the person within the first field of view; outputting, usingat least one of said speaker and said visual indicator, feedback to theperson indicating that the person is in the first field of view and thesmart-home device is ready to detect and process a gesture; processingreadings from at least said radiation based sensor to determine that theperson has made a particular gesture; and performing an actioncorresponding to the particular gesture.
 17. The method of claim 16,further comprising: determining an orientation of the smart-home devicerelative to a room, wherein said acoustic sensing system is operable todetermine presence in each of the first field of view and a second fieldof view; and responsive to a detected orientation of the smart-homedevice relative to the room, disabling one of said first and secondfields of view of said acoustic sensing system.
 18. The method of claim16, further comprising processing readings from the radiation basedsensor to determine whether a periodic pattern exists that is indicativeof a periodic hand waving gesture.
 19. The method of claim 16, furthercomprising emitting, via the speaker, voice instructions to the personwhen the person is detected to be within the first field of view. 20.The method of claim 16, wherein the event is a hazard alarm event inwhich a buzzer is activated, and wherein the action performedcorresponding to the particular gesture hushes the buzzer.